Zain was cursed by the witch as a way of revenge due to him killing one of the witch's family members.
Oliver definitely uses his position as mayor to benefit his criminal activities (and getting his vengeance). The two livelihoods do come into conflict quite frequently. A great example of this is when he revokes the Superhuman Vigilante Act, forcing heroes and villains alike to pay for damages caused by fighting.
Namys is rarely in contact with Set. (Originally created him for a old, defunct rp.)
Lux lost his kingdom when it was overran and invaded by someone that his parents had thought to be a friend. He plans on taking it back with the help of his adopted niece and nephew, who were also betrayed by the person that took over his kingdom.
Clownface indeed uses his position as a cook to pick out his prey, taking advantage of overhearing conversations and plans that certain students may have for the weekend to use for an opportunity to abduct them.
Spoiler - click to show.
He disposes of bodies by turning his victims into the food served at breakfast and lunch.
(I'm willing to share the story he's from eventhough it's still in it's wip state.)
Davis claims to be heterosexual due to being in denial about his sexuality. He's mostly embarrassed about being confused about his attractions, and does occasionally worry about what might happen if his friends, family, and peers were to find out the truth.
Alix lost part of her finger by slicing it off with a hidden blade. (Think modern-day Assassin's Creed here.)
Lux, while influenced by his curse, made a plan for Lumen to "kill him." Knowing that it would be strange for him not to retaliate for being stabbed in the back (literally and figuratively here), he, on a whim, sliced off Lumen's hand.