This technically references an alternate multiverse (?) idea, which was born out of listening to the song Hell is Mine. So, yeah, there technically is context (with two possible endings!) to this.
"reaper sans is a confident flirty pervert whose only personality traits are being gay and simping for geno looll"
okay cool but did you know that when he was one of the newly created death gods he hesitated to reap chara when they were murdered because of the compassion he felt for their determination to live which ended up causing the reaping to fail and cursing chara to be corrupted forever and he will never stop blaming himself for what he did ? that he no longer hesitates to reap souls or seems to have mercy when he does so even if he feels terrible about it because of the heavy amount of guilt he feels every day ? that chara is the bane of his existence because they are a visual reminder of his mistake ?
did you know he views life and living as something negative for the reason that when people are alive they have to feel pain ? and he used to despise life because he had to see how people were suffering from simply being alive when he was doing his job ?
did you know he hates his job and just wants to be himself in peace but he can't because reaping is what he was created to do ? that every single thing i listed above are just a few examples of his chronic depression and nihilism that shape how he views the world ? I CAN KEEP GOING !!