So.. canon Vulcan's past was surprisingly traumatic/tragic. Or, for some people not so surprisingly. He was actually a lot like present Spade back then. The things at fault for him becoming a sociopath was: ~ Magma ~ Resentment, hatred, and jealousy(mostly towards his brother, but towards everyone really, as he wasn't "normal" but he wanted to be, he hated everything about himself, his rings, his teeth, his eyes, everything bc they were considered different) ~ His mother ofc ~ Just basically everyone forgetting he exists bc he kinda sunk into the shadows with how little he liked to interact yeah, also Zane, if u wanna see more of Vulcan's lore, just tell me lol, his lore is kinda a "THERE IS NO WAY THAT'S THE SAME PERSON" thing
Note: He did genuinely love his brother(Spade) at some point, but that envy slowly turned into jealousy which slowly turned to resentment which slowly turned to hatred and yea..