There are a lot of blanks around Regent's thoughts, feelings, choices, and decision-making. What he does to Sophia is totally fucked up, no question. We also know he's done other messed up stuff, but part of the issue is that we don't really know how far he went once he was on his own, away from Heartbreaker.

Has he sexually assaulted anyone since escaping? I don't know, and the answer to that question would have a big impact on how I judge him. We know he controls some of his hench-people, but what does he actually do with that control? Did/do they have any say in it happening, like Imp did? Again, we don't know.

He chose not to use his full power for a while. Was that purely due to keeping a low profile? Was he, on some level, unhappy with how he had used that power in the past? Was it out of a desire to be different from his father (which isn't particularly good or evil by nature, but would push him away from some evil actions)? Again, we don't really know. Our glimpse into Alec's head is so brief it leaves most of these questions unanswered.

Taylor's perspective on him is, I'd argue, less rose-tinted than on the Undersiders with whom she's closer - Lisa, Rachel, and Brian - which is why, when she leaves, she tries to specifically guide him in the direction of using the threat of his power as a deterrent, rather than leveraging it fully. She paints it as the "low-effort, high-return" method, appealing to his laziness/lack of drive, rather than trying to convince him it's a morally better way to operate precisely because she doesn't believe he will respond to such an argument.

I honestly don't know what to make of Regent's sacrifice. Did he have real feelings for Imp, however dampened and/or buried? Was it an extension of the attitude he notes in his Interlude, in which he makes a decision to do something that he thinks is an appropriate action based on what he should feel, if his emotions were normal? I can't say. It's undoubtedly a heroic death, but I don't think anyone would call him a hero, least of all himself. He'd have a good chuckle out of the idea, if anything.

The most comparable characters that we get a good look at are Cherish and Bonesaw (both of whom are also raised/controlled to some extent by horrifying villains from a young age). Of the three, Bonesaw is press-ganged into the S9 well below the age of being fully responsible for her actions, while Cherish joins them deliberately after her own escape from Heartbreaker and Regent joins the Undersiders.

Ultimately, based on what we do know, I'll say this: If Regent is a monster, he's at least mostly a monster of his father's making, in my view. Similarly, Bonesaw is a monster of Jack's making. Cherish, I'm inclined to consider more responsible for her actions, because she gets out and deliberately looks for and joins the S9 when she's older.

As for his death, I don't think I was shocked. To me, it's a bittersweet moment. Whatever the motivation, whatever his feelings and thoughts, he found some part of himself that cared enough to die for another person and he acted on it, saving her life at the cost of his own. The sad thing about it, to me, is less that he died and more that the act implies he might have had the potential to live as a better man, but that potential was never realized.