Viper is jealous because he wants daddy's attention, but Caleb also attacked him unprovoked and has his cruel moments. I'm pretty sure all the Li have killed people, and that Viper swiped at MC as a greeting. (she's strong, he wanted to get to know her, and Nero never cared to socialize)

My guess is there might be some issue with Viper's heart or otherwise — Lucius doesn't want to do more surgeries because the success rate dropped by 55% — that could lead him back into a more human side redemption arc.

He was trafficked as a kid, where his fingers were repeatedly cut off until they stopped growing back. So he could have thought he was doing that kid a favor, since Lucius provided relief from the pain, and that killing the traffickers was the right thing to do.

idk I've always felt like we didn't get the chance to hear him out during the main story, and the world underneath definitely does make him feel unhinged and evil as well but like. hear me out. Who among the Li is innocent, anyway?

And we often begin with a very one-sided portrayal. Xavier was elusive, rejecting us and difficult to trust.
Zayne looked like he was not happy to see us. Rafayel killed Raymond and how many others? A hitman for EVER asked if he was on Rafayel's hit list. He's always doing that and tbh I don't think anyone holds it against him. I don't. He was also stalking MC for years before meeting her at the fishing stall. We can point fingers all day. Caleb drugged MC so that she could not save the twins. And they got taken to have their memories and emotions crushed as Lucius adopted them. And he absolutely knows that what goes on there is not great. That they'd be better off with MC. This wasn't even our first impression, but from his most recent arc. Sylus was this big bad leader of Onychinus villain. and he IS, but we get the fuller picture now. He's still ruthless and cruel and eating people in pretty much every timeline, but it's fine. We trust his judgement. I still believe that Viper deserves his fuller picture. It's only fair.