These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Dr. Tomohiko Katsuragi is the Saiki clan's doctor and one of Souma's lovers. He initially appears to be a polite, helpful doctor, but is soon revealed to be a disgusting pedophilic rapist and multiple murderer. When Souma informs him that his stepmother Sakurako was sexually abusing him, Katsuragi drugs Sakurako and forces the traumatized young Souma to slit her wrists and kill her, not to stop the boy's suffering but so he could have Souma for himself. He regularly rapes and tortures Souma for years, before doing the same to Masataka, Souma's lover, out of jealousy. He gives his wife Asayo the same treatment, turning her into a battered Broken Bird. He later tries to poison Souma's ill father Lord Saki as well, one of the few people still remaining to him. Out of the many horrible people in this story, he's definitely the worst.
Draco in Leather Pants: Yes, Souma has a heartbreaking and terrible past. Yes, he's no Complete Monster. But he did mentally and sexually abuse the first person that gave him real affection in a long time, and no Dark and Troubled Past justifies or handwaves that. Even Souma himself deeply regrets what he did to Masataka, fandom!
Ho Yay: In addition to the obvious Yaoi relationships, there's a lot of hints that some side characters are attracted to Souma.
Considering that it's Souma, odds are they've slept with him already.
Jerkass Woobie: Souma and Sakurako. Both have heartbreaking pasts and big reasons to be the way they are, but it's NOT a justification for the shit they pull on others.
Magnificent Bastard: Souma has traces of this, specially when he brilliantly and spectacularly punishes Katsuragi.
The Woobie: Poor Masataka. And Asayo, Katsuragi's wife. And the young maid that was Souma's mistress and got pregnant with his baby, then was tortured by Sakurako, lost her baby and ended up horribly broken.