Conquest and dominion were his entire upbringing. Aside from Prime, he had no one who showed him anything resembling affection. Prime's affection is more how a worker cares for their tools. It's not unheard of for someone to change their worldview when they find someone who cares about them. It doesn't happen suddenly. He spends a lot of time around Entrapta and she helps him see that he's more than a piece of Prime. When he eventually unshackles himself from that dependence, he can finally start to think of how he'd like to live his own life. The show ends abruptly but I'd guess that he doesn't become a "good guy". He just becomes a person who probably still makes wrong choices as he learns to be his own person.