Things i think would be really funny: the gang gets used to Halsin just sort of. Slumming it around the camp as a bear, sometimes. It's warmer to sleep, and sometimes he'll snuffle into the food stores to break his fast as a bear and then amble off into the woods to bathe and then come back as a person. Some people require caffeine to be human in the mornings - Halsin requires cold water and time to wake up. And before long, the rest think nothing of it. He never harms them, after all. They still speak to him in passing or stop to ruffle his fur. There are jokes about being surprised no one has caught Astarion - who can't regulate his body temperature anymore - using him as a blanket yet.
Except one day, Halsin the bear trundles into camp and curls up in his normal spot near the fire...while Halsin the elf is still talking to Karlach. There is a moment of dead silence and bewildered looks, which turn to dawning horror as they all realise that there have always been two Halsins, and all this time one of them was a whole-ass wild grizzly bear.
The silence is broken by Astarion - who's known the whole time because he can smell the difference - laughing himself stupid because he tried to bring this up ages ago and has been under the impression ever since that the bear was known about and allowed to be there.
("That's not - is? Is anyone else seeing what I'm seeing? Anybody going to do something about - no? Really? We're all just treating this as normal, are we?"
"Leave him alone, Astarion. He's not a morning person."
Well, alright then. It's not like Tav doesn't regularly take in mangy strays. How was he to know which you are keeping and which you aren't, darling?)
(The bear hasn't harmed anyone, and a quick Speak With Animals reveals that he's not inclined to: he likes the warmth and the free food. So they end up deciding to just. Let him do his thing.)
Orin: slut! WHORE! I cannot WAIT until Father punishes you!
Durge: *slams fists down onto the table* You don’t understand! He’s a handsome man with an easy smile!
Orin: he’s a tyrant with a paunch!
Durge: *flips table* I’m not discussing this with you; you’re just envious because I’m able to bang someone without killing them! I mean, look at all your past “girlfriends”!
Orin: *puts her hands over the external auditory meatus of a skull she’s holding* How DARE you! Hush, don’t listen to him he doesn’t understand love.