My guys, my sillies. So so so so silly, oh silly-vanilly!
So... where do I start?
It's a combination of things, I guess. I know a lot of people think it's distateful, because of their past and the complex morality when it comes to Shadow Milk, but that's exactly why I like it so much. I like the idea of healing and becoming someone better, and that's kinda the concept for them. It's true that Shadow Milk has done horrible things, and has hurt Pure Vanilla, but Pure Vanilla himself is aware that Shadow Milk is not in the right mental space, hence why he points out the loneliness thing.
Pure Vanilla wanted to give Shadow Milk a chance to start his healing process, that's why he tried to become his friend. Shadow Milk rejected, and I believe that's out of fear. Healin IS scary when you've been mentally unwell for so long. That mental struggle has been a constant, stable thing for you, and letting it go is scary. I want to believe someday, Shadow Milk would finally accept Pure Vanilla's help, and he'd become his support through the process. They ARE each other's half, meant to be together, they understand each other more than anyone else in this world.
Also they're the meme of "Someone will die-" "-OF FUN!" and I think it's very funny.
First fanart (the one with Truthless Recluse) was made by GinjaNinjaOwO! Second one was made by Ang1079577 on X
(this is still a wip! I'll try to add more stuff in the future!)