#rwby raven brawen

[n6918]

Could we get Raven x Ren headcanons

Lewd RWBY Headcanno Forest Flowers (Ren x Raven)

After being kidnapped by Raven, Ren is blackmailed into becoming her sex slave in exchange for not attacking villages. He takes his frustration out on the situation as he mercilessly pounds her pussy. Just as she intends, screaming and wailing from her tent. 

Raven requires him to wear, collars and shackles, and a leash of chains leading to her. With the only other clothes, she’s allowed to wear being a line cloth. She often brushes it aside to play with him, or suck him off when she’s bored. The other women of the tribe can often be, seen staring and watching him longingly.

When in the privacy of her tent, Raven surrenders herself to Ren. Allowing him to abuse her sexually and release his frustrations along with his semen. She finds it exhilarating the way he chokes her out and comes in her pussy.

For his part Ren has discovered a kink of his. He enjoys face fuck, holding her shoulders down and pounding into her throat. But it’s mostly the fact that he can force his cum down her throat and drink it. That makes him most excited. 

[ninjasofl0v3]

Raven just so used to her brother’s antics. What’s that? Qrow’s drunkenly stumbled into the camp? He’s bent Raven over a crate? Yeah whatever, she’ll just go on her scroll and let him finish himself off before he passes out and she carries him home to leave on Tai’s doorstep

This is absolutely based on some art I saw but i dont know where it went 😭

🦋 content!: incest — brother / sister. free use. drunk sex. public sex.

even with all these years apart, qrow still knows that his sister's pussy will always be his so can raven really blame him when he finds her & shoves her over whatever objects closest to sink his dick inside that tight heat. panting & groaning as he humps her cunt like a dog, litters her skin in bites while she all but ignores him & it pisses him off so bad but he wants to cum more than he wants to choke her out.

of course once he's spilled his cum inside her pussy, raven is more than happy to let him stay inside her while she idly plays with her clit, qrow passed out & slumped over her. she'll take him home, eventually. for now she'll use him like the community dick he is.

[rwby-oscar-blog]

Goes to check in on Oscar after being caught by the milfs, he tried being quiet since he didnxt wanna be captured as well.

(Gotta check on my dude, make sure he's okay or needs back up.)

As you open the door. You see Oscar soundly asleep with passed out Team Rwby, their mothers and Nora right next to him with Oscar seed leaking out of them. Apparently all the moaning from the room alerted the others. They didn't want to be left out so they joined in. Which is also how they found that there's more to the rumor. A LOT more

[paodocinh]

Can you draw more plus-sized Summer Rose? Do you have other body diversity headcanons in RWBY, such as Qrow with a beer belly?

Hellooo lovely anon!

god, when i saw this ask i went absolutely ballistic. No words can explain just how much I adore my hcs of Summer Rose, she's my favorite RWBY character because the little details i added to her character as hcs just kind of made it for me, even if she has next to no screentime in the main series.

Personally, in my aus, i have tweaked and changed a LOT of the main cast so it'd have more representation. I couldn't draw all of them sadly, but here goes the little list:

Body diversity HCS ->

1. Blake Belladona is poc! This is the more obvious one but I decided to make her a dark-skinned woman as a general hcs in everything I do. You could also go further and say that her hair texture is different, and that she just straightens it.

2. Yang Xiao Long has a muscular build! (No shit sherlock) but yeah, she's buff! Give the girl her muscles! I also made her anatomy a little bit less off and she probably has a little belly too, because I can't really accept that she's so thin while her breasts are completely disproportionate to her body. She's also tanned!

3. This isn't exactly my HCS, because I haven't specifically added them to any AU, but I really like @peixedobar's take that Weiss Schnee has albinism.

4. Ruby Rose is also a bit stronger physically! She isn't as buff as Yang or Raven, because these two are absolute units, but she also isn't as thin as she is in cannon.

This is also more prominent for my Zombie!AU because Ruby lends Crescent Rose to Oscar for a good part of the plot, and after that she just... fucking punches everyone to oblivion. (I know it's a bit OOC but in-universe it makes sense)

5. Lie Ren is blasian! I don't really know where I got this from, but while thinking to myself about what I could do to make my Zombie Au more inclusive, the thought just crossed my mind. His hair is also textured, he has braids.

6. Raven Branwen is fucking jacked. Seriously she's probably the most well-built character I can think of in my AUs. She isn't like a massive war tank(or similar to League of Legends Illaoi for example) but she is very in-shape and has very well-defined muscles along with a body adorned by scars. Aside from that, she's also part asian, part... Brazillian? More elaboration on that on Qrow's part lmfao.

7. Qrow Brawen with a fucking beer belly LETS GOOOOOOOO!!

Anon, when you suggested that, i went insane. It had never crossed my mind, because I often drew Qrow with a very muscular build, mostly out of anatomy studies — But gosh, I adored this hc in so many ways i'll probably add it EVERYWHERE. QROW WITH A BEER BELLY SHALL BE MY MARK ON THIS PLANET.

Aside from that, I also made his face more detailed. Usually it was difficult for me to draw him because he lacked a lot of facial details that often make irl people more unique, and I believe that's due to RWBY's artstyle. On mines, however, he has beauty marks below his right eyebrow and one above the right side of his lips. Scars all over, too.

He has a Japanese descent(Assuming that The Branwen Tribe is from Anima + Raven's choice of wear cannonically) and asiatic features on his eyes, but him and Raven also have heavy latin-american characteristics. They're Brazillian in my aus, mostly out of a inside joke(I too am Brazillian) and the fact that Qrow gives me a lot of latino vibes(Contrary to popular fandom belief, his hips do not lie !!!!), but after a while I started noticing that It actually wouldn't be too far-fetched to believe this, because if you look back at the history and relationship between Brazil and Japan, you'd find that these two countries actually have a LOT of story together!

Brazil homes a bunch of different cultures and ethnicities in it's lands, it's a country with a lot of diversity so in my opinion it wouldn't be too otherworldly to make The Branwen Twins brazillian in my aus :p

That's it for body hcs! I'll probably have more in the near future, but for now these are the ones I can remember.

Other diversity Hcs ->

1. Autistic Penny, Ruby, Summer Rose(this wasn't on purpose, it just happened as I was writting her LMFAO), Neopolitan

2. Transfem Nora, He/They Lie Ren

3. ADHD Jaune, Qrow Branwen

4. This is specific to a AU I have, it isn't present in my other works, but in La Vie En Rose(Royal Au) Neopolitan eventually has a leg injury during a major plotpoint that leaves her disabled, so her Parasol is also used as a cane of sorts since she can't be as agile and flexible anymore. She's still slaying though, always.

5. Summer Rose is blind of one eye!

I'm quite sure I forgot a few, and with time I'll update you on everything, but for now these are the ones! Thanks for asking, Anon!

And just as you asked for~ A lovely Summer Rose on a Beach day for ya!

[canonrpfinder]

Hi! I’m looking for 18+ roleplayers in the RWBY fandom. I write anywhere from 1-6 paragraphs depending on my mood. I’m fairly open to ships as long as they’re not morally incorrect. All I ask is that we roleplay on Discord as it is easier for me. My muses for the andom will be listed below. Like this post and I’ll get back to you. I might be willing to play other characters, we would just have to talk about it beforehand. With that being said I’m also okay with platonic interactions. 

~Muses~ 

Weiss Schnee

Blake Belladonna

Yang Xiao Long 

Pyrrha Nikos 

Lie Ren 

Raven Brawen 

Cinder Fall 

Neptune Vasilias 

Winter Schnee

~Ships~ (I’m open to other ships as well, these are just the ones heavily on my mind) 

Blake x Yang (can play either) 

Pyrrha x Jaune (can play Pyrrha) 

Nora x Ren (can play Ren) 

Sun x Neptune (can play Neptune) 

Weiss x Ruby (can play Weiss) 

✒

[rwbyazre]

Love Vernal's redesign! Did you change anything else about her?

Thanks!

I hadn't really changed anything to Vernal as really just add to her character than what we got in RWBY.

Vernal was born in the Brawen tribe, which is pretty standard for anyone in the tribe. Because of their infamous reputation, many believe that the Branwen tribe takes criminals and traveller alike into their tribe, either willingly or by force, to build up their numbers and pose more of a threat to Huntsmen sent to hunt them or settlements they raid.

They don't, and the only one to actually come out of the tribe in Raven's time was Odstesteg, and that's only because Raven saw the maiden powers as something beneficial to the tribe.

Vernal as a child was completely different to how she is as an adult. She never saw the world outside the tribe, and was constantly told by her mother that she wasn't allowed to leave because it was too dangerous.

But she didn't listen. She loved how Mistral settlements outside the main cities held onto their unique colours, using flowers and plants throughout to bring life to their homes, and so she would sneak out of camp every time they came near a settlement ahead of a raid.

She was a fish out of water, never interacting with people outside of the tribe, and so she would stick out and be avoided by the people. The first time she went there, she saw a stall laid out with beautiful jewellery from traders that came by.

Vernal stole them, taking them back to the camp and hiding them away in a little stash. More and more, she would steal and add to the stash, keeping it hidden from everyone to avoid her secret being found out.

But one day, she tried to take an ornate mirror that she spotted and was caught by the guard. Before she could be arrested, Raven suddenly appeared and killed the guard, taking Vernal and the mirror back to camp.

There in front of everyone, Raven berated Vernal for endangering the tribe over stupid trinkets, smashing the mirror on the ground to prove her point. Vernal was just six at that point.

That incident stuck with Vernal afterwards. She didn't leave the tribe, kept to herself, and just did what she was told. But she was miserable.

A year after the incident, she was outside of the campsire gathering materials with her mother, only to be discovered by Odstesteg. She just ran away from Haven, lost and hurt, but Vernal was very suspicious and wary.

It was her mother that decided to take Odstesteg to Raven. Odstesteg was allowed to stay, but only because Raven found out she was the Spring Maiden and decided to train her into a soldier for the tribe.

Vernal started to grow jealous of the attention Odstesteg was getting from Raven, still struggling with the trauma a year prior. She would follow them everywhere, watching Raven's intense training that she subjected Odstesteg to. She wanted Raven to see her.

So, Vernal started training by herself. Every day, for years. She went to design her moon blades herself, showing an intelligence that the others couldn't match, not even her mother who showed her how to engineer in the first place. She was proud in Vernal, but it wasn't enough for her.

By 77MTP, Vernal was a deadly fighter at just fourteen, but Raven didn't acknowledge it. She was busy training Odstesteg, who was not as promising as Vernal.

On one night, they went to attack a settlement, using the dark to their advantage. The problem was that the chaos drew in the Grimm faster than Raven predicated, causing the tribe to get caught up before they could escape.

Vernal escaped with her life, but was clawed in the head by a grimm, leaving the scar on the top of her head that's in her design. She saw Odstesteg struggling to fight off the waves of Grimm, finding that there was a chance to save her. But she didn't.

Odstesteg was mauled before Raven could save her. Dragged back to camp, Vernal was in the tent while the doctor tried to save Odstesteg, but she passed away. There, she saw the Maiden powers go to Raven, which is what she didn't want.

It was at that point that Vernal was brought into Raven's secret that she learned from Ozpin. Salem, Maidens, magic, and at first Vernal didn't believe her, but Raven managed to convince her. That night, Vernal agreed to be the fake Maiden, putting the target on her back for Raven.

Finally, she was getting the attention she wanted. Raven took over her training, teaching Vernal skills she knew, but Vernal didn't know that Raven kept her own skills to herself so that Vernal couldn't excel too much and risk overthrowing her.

By the time of the Fall of Beacon, Vernal is seventeen, and turned eighteen in the timeskip between V5 and V6 of AZRE.

She'll be given more scenes to flesh her out during the Mistral arc, as a lot of the events are moved around to fit the timeline.

Spoilers ahead.

Vernal still dies in the Haven Vault, killed by Cinder to try and take the Spring powers. The tragedy is that Vernal wanted Raven to look at her after the abuse when she was a child, sacrificing Odstesteg for her own needs, only to have the same done to her by Raven.

[cowgirlbeepboops]

rwby characters as dumb things my discord friends have said

ruby: the g spot is where the gamers hang out

weiss: once again, i was abandoned. it’s okay, i have a sword to defend myself

blake: i have seen someone make tentacle porn with that

yang: your balls WILL hang from the back of my truck

jaune: who needs a nut chopper when you have 36 years of repressed feelings

nora: my asshole usually baja blasts after eating taco bell

pyrrha: getting jiggy with it! i want to leave my worldly body.

ren: please leave my asshole alone

sun: your pecs could shoot me into the stratosphere dude

neptune: fear is stored in my balls

summer: it’s not bleeding anymore but i would still like a bandaid!! the nipples will have to wait.

taiyang: you’re so warm and you make me happy… like piss. you’re my little pissbaby <3

raven: you got a god complex? die on a fucking cross

qrow: no i don’t have a piss kink, i’m infertile remember?

oscar: what does kfc stand for? kentucky fucking chicken?

penny: wow girlqueenpussyboss. that fart you ripped was stinky. come and kiss me on the mouth.

ozpin: what i am about to do has not been approved by the vatican

salem: you know what? at this point, “i’m sorry” isn’t enough. grovel, bitch.

hazel: i retract any and all apologies. shut the fuck up.

watts: don’t dab up the homies, that’s how you get syphilis

tyrian: is it okay if i send tom and jerry smut

cinder: i cannot kill the part of me that cringes so i’m gonna kill you

emerald: at least you weren’t a light yagami kinnie at the age of 12

mercury: pass the pussy brian, i know you have some

[jauneda1]

Authors not: This is a alternate timeline of the ANNIHILATION AU. I know that's odd for most but I've always had a multi timeline theory planned so here we go.

Alt Annihilation Au

Pain... Sister... Friends...

"What are these words to me?"

CRUNCH

The sound's of an Atlas grunt getting his spine bit through and the thud of what's left of his head hitting the ground was enough. To spark light into fallen knight currently eating his kill.

"What am I doing... I mean I know what I'm doing I'm dreaming this is all a bad dream right."

......

"There are so many of us we are going to overwhelm them. This checkpoint wasn't meant for a hoard of our size. This should hurt at this point I've taken a bullet to the chest but I barely even bled...."

"Dream or not this hurts. That pissed me off YOU GUYS ARE FUCKED NOW!"

As his mouth splits where his cheeks used to be and the chin snaps and flys open. Allowing for our knights bite force to be stronger and gore his targets. He lets out a loud roar shaking and terrifying the grunts paralyzing a few. The checkpoint of Ansel fell that day.

"This house... It feels... Familiar to me... "

"Mom..Dad... Family..."

Then and only at this point the fog was lifted. The knight fell to his knees in pain and regret running through him. He could feel his body getting ready to upchuck the last grunts he feasted on at the checkpoint 20min ago. As Jaune let everything in him flow out weather it be tears or bits and pieces Jaune let it out finally clearing the fog, the darkness, the sadness, the pain of being undead. Jaune was alive now. He was himself again but with obvious side effects.

"Jaune...?"

The patriarch of the Arc household asked.

Jaune turned his head eyes no longer red and black but they're bright blue form. Bringing the light back into his father's eyes. Come now boy there's more infected outside. The two went deeper into the home as if nothing happened. Isaac hadn't even questioned his son after watching him turn human again he had came into this house a monster. But Jaune's father needed not to. Once he saw his son's baby blues and the look they had on them Isaac knew that his son was human again. It's not the same look his eyes had 2 months ago at the fall.

Two months ago the fall:

"This is Lisa Lavender going live at the scene of Beacon academy. "

Lisa explains that there seems to be a virus infecting the populist of Vale as a white fang grunt runs past her with a sizeable bite taken from his arm. Then the camera man focused on a figure rush towards the new team. The fallen Arc was currently rushing they're position untill the sounds of gunfire made him come to a halt then he dropped to his knees and face planted. The grunt was currently in the cameras view so only a few people were able to make out Jaune getting up and his jaw snapping and revealing his new Grimm form. His body darkened to a light brown tan, his hoodie and pants in rags he was obviously torn apart by atleast 10 infected, but his body was healing even now. He's also missing his classic chucks hight tops. It's just barefoot and half naked arc with a his jaw in two ready to tear this grunt open. This is exactly what happened but the camera man was in shock so all he did was record as Jaune tore into the grunt then into Lisa Lavender. Then his sights were on the camera man. The man dropped the camera and dropped to his knees praying to whatever god he thought was going to save him.

After killing the three and taking in the moment Jaune looked at the camera which was still live ppl weren't able to cut the footage so everyone looking in sees this. His team who where currently on a bullhead surveying the situation and team RWBY and everyone who knew him or of him saw the monster he had turned into. Jaune walked over to the camera and stomped on it. His subconscious trying to hide him as he is now from those who could see him. Jaune started sprinting in the direction of any noise the only thing is all the noise he can here was towards the checkpoint at the edge of the city at the Taichi bridge, The only way in and out of Vale.

"Jaune? Come on its time to go."

Jaune was pulled from his thoughts everything is still coming back to him. But his father wasn't going to lose his son.

"Listen Jaune there's a bull head that we can take to a safezone we just need to get to the middle of town. "

"Dad?... Where are my sisters...Where's mom?"

"They're safe there in Mantel but were going to Mistral we need to speak with Ozpin and figure out where to go with your situation."

" Jaune this may sound harsh but you weren't the run of the mill infected. On top of that your the only infected to do what you do. Your also the only person to revert back to your humanity. Your one of a kind and probably the only one who can save Remnant from this virus. "

One week later:

"Jaune let me know if this ear piece works?"

"Dad it's fine."

"I'm just checking in on you jeez when did you get all moody."

"WHEN... When I realized that the dream I was having turned out to be me killing people for 2 months straight..."

...

"I'm sorry dad it's just..."

"It's okay Jaune I'm sorry for being like that. On better note you should be just outside of Haven Academy you can just walk in and finally take off that hood and show your beautiful face."

"Dad... There's still scares from when I was infected."

"Yes but now tanks to me your aura is back and your healing."

"But what if I see some one I know?"

"Your bound to see someone you know. "

"Just remember your here to speak to Ozpin."

...

...

...

The doors to the academy open the first to see the Arc is of course Leo and Ozpin.

Then everyone else including all of the main students, Team RWBY,JNPR, CFVY, SSUN and Three people Jaune has never seen before. Two of them had crimson eyes but one of them was chuckling to himself before pulling out a flask and drinking. The woman put one hand on her the hilt of her blade. While third caused Jaune to double take and speak out loud in a questioning manner but definitely confused.

"R. Ruby"

Is all he could attempt to say before he realized most of the people in the room where looking at him with fear till he spoke and some of the ppl now where backing away from the entrance.

Well from what I can here son it doesn't look like they still have a kill order for your head.

"You tell me this now."

Jaune also said this out loud.

[breezysketch]

“So there we were, standing in the auditorium, looking at Qrow wearing a skirt-“ (that scene with Tai and the other professors in v4 is also so sweet to watch but also it’s funny to think about)

[n6918]

Can we maybe get some lewd headcanon for Raven x Ghira (mating season & breeding) btw love your work

Lewd RWBY Headcanno Feral Feline (Raven x Ghira)

Raven may have thought that kidnapping the leader of Menagerie was going to be quite profitable, and she may have even thought that having a little fun with the handsome man is going to be harmless. But one faunus heat cycle later, she would learn the consequences. Ghira escape the band, camp with his new pet in tow playing with her plump ass well he tugs on her new leash.

Raven is now a breed toy for the powerful politician, a fitting punishment for her crimes. She now lounges around the mansion and barely any clothes being taken by him whenever he wants. Many times, spending the whole day under his desk, pleasuring him while he attends to the business of state.

Ghira loves to have her clean his cock after a good breeding my using her mouth. So he keeps her hair in a ponytail so he has good control of her head. 

He often makes Raven watch him fuck his own wife before bed, only sending her away when they were done fucking. Watching his pet play with herself well he pounds Kali is very empowering. 

(Thanks for the compliment 🥰)

[bridgyrose]

May I ask for more Summer is Queen of Vale AU, please? Thanks to her new heart, Summer is able to tell that Raven's getting anxious and asks her what's wrong. Raven suggests that it may be time to tell Qrow and Taiyang about their relationship, which Summer agrees. They then find Taiyang and explain that they're in a relationship. Surprisingly, the blonde explains that he had some assumptions. Thankfully, he then hugs the two warmly, saying that he's happy for them and will support them.

Summer took a look over to Raven, pausing as she could feel the anxiety pouring from her. For a moment, she thought she was imagining things, but the longer she watched Raven, the more she could feel her emotions pour out of her. “Rae? Are you okay?” 

“I’m… fine,” Raven lied. 

“I know you’re not. I can feel it.” 

Raven sighed and slumped back a bit. “Right, grimm heart… of course you can tell my emotions….” 

“So, what’s wrong?” 

“It’s… Tai and Qrow. I think its time to let them know that you and I are… you know…” 

“Dating?”

“Yes.” 

Summer nodded, thinking about it for a moment. “Well, it would be about time, wouldnt it?” 

“It is. And honestly, it feels a bit weird doing all of this while they dont know.” Raven sighed and laid back on her bed, looking up at the ceiling. “Sure, I didnt want them to know at first, but now… we’ve been together for a couple months and I’m ready for them to know.”

“Know what?” 

Raven hesitated as she watched Qrow and Tai walk into the dorm, pausing for a moment. “O-oh, well, you know-” 

“Raven and I are dating,” interrupted Summer. 

Taiyang looked between the two and shrugged. “Cant say I didnt see it coming. The two of you have been awfully close together lately.” 

Qrow sat down to start studying. “As long as you didnt kill someone, then I’m happy for you, sis.” 

Raven blinked for a moment as she listened to her teammates. “W-wait, that’s it? You just… expected it to happen? No surprise? No…. astonishment?” 

“If it makes you feel better, I sorta expected you to say that you ended up pregnant.” Qrow smirked as he looked up at Raven. “Or that you killed someone and needed us to help you bury a body.” 

Raven shook her head. “Of course you’d expect that.” 

Taiyang chuckled and smiled a bit. “I mean, with how much time the two of you have spent together, I’m honestly a bit surprised you didnt just tell us sooner.” 

“If you knew then why didnt you say anything?” 

“I figured you’d tell us when you were ready.” 

Summer relaxed a bit as she watched her team, glad Tai and Qrow were supporting them, even if Raven wasnt exactly expecting this to be the outcome. Either way, she was glad that her team was willing to support her with anything, another reason she knew that she picked the right people to trust. 

[briansastro10]

KAMEN RIDER SABER X RWBY AU Part 3

This is the part 3 of the character draft of my crossover fanfics, on this one i will be introducing the megid of the series

 Raven As Desast:

-The Other Swordswoman that went rouge on the organization -Tai was forced to sealed her and lied to yang about her mother disappearance -Is the one who killed Tai right infront of Ruby -Tries to bring Oscar to her side.

James Ironwood as Master Logos / Kamen Rider Solomon

-Instead of the maniac on the Saber Series, he is more of a military dictator -with all of his morals circles on Power/survival at the finest -decides to wipe all "weakling" -consider Ruby and all of the people who defies him as "weaklings" -He had a god complex, wanting the power -Eventually became Kamen Rider Solomon -But he was manipulated too easily by Cinder

Ozpin as Victor/Tassel

-He was Jaune's Guide/Old friend -the first married couple in wonder rider world -Ozpin saw the death of their Childs and what their family death meant to Salem -He had no choice but to seal her -He wasn't there, he cant see to see the woman he loved sealed forever..

Mercury as Legeiel and Emerald as Zooous:

-they were few of the early people to enter the Wonder Rider World -He was the carer of the group on his early life and she the presentation of love -They both loved each other on the past -Everything changes when he had the power. -They grew to hate each other -they cast their humanity aside -They sabotage and fight with each other -But when Mercury Died Emerald had anger and doubt, then she lashes it out to the Water Swordsman Weiss

Cinder As Storious:

-always been the tactician of the first people -always think a step ahead -Manipulated all of them in Saber -The true main villain of Saber

Summer Rose as the one Who connect both world Luna:

-She was there for Tai, after he sealed Raven -Summer helped him out from a dark place -along the way, they fell in love and made Ruby -Unluckily she was the bride to connect both world and the master Logos brought her as a sacrifice -This time it was Ruby who was the one that made the promise, to save her mother

Pyrahh as Sophia:

-She will play the role Of Sophia, -had a history with Jaune back when he was human -Probably might become Calibur

That's all i have for the cast, although i have problem figuring out the Mei Sudo of the Series. If you have any idea, I'm open to suggestions

[thesassiestcolor]

[mastersara]

Birds of a feather.

[luimnigh]

Y'know, every seems to come up with theories as to why Ruby's last name is Rose, her mother's, while Yang's last name is Xiao Long, her father's.

Guys, I hate to tell you this, but the reason is pretty simple.

When people are married, their children usually get their father's last name. When people have children outside of marriage, they usually get their mother's last name.

Raven and Tai were married, Amity Arena says they were, and it's entirely possible they didn't get a legal divorce. Tai probably could have filed solo on the basis of spousal abandonment, but given how he talks about her, there's a decent chance he still loves her on some level. That would make any person hesitant.

(And even if Remnant has legal polygamy, you'd probably need the permission of both parties, and that's something I don't think Raven would give.)

So Ruby was more than likely born out of wedlock, and was thus defaulted to her mother's name. Now, you can get that changed, but Summer died before Ruby was old enough to have an opinion on such a thing. Which would make anyone hesitant to change their last name.