Apologies for my brazenness, honored elder dogclapper, but I have to disagree.
From my point of view he started taking the drugs because they were given to him by people he trusted, and also partially, because he was still a child. After that he couldn't really go back, even if he wanted. He certainly doesn't regret it, I'm aware, but I'm also convinced that a hunger for power wasn't the main drive behind it all. He had siblings, "friends" in Alice and Klaus, even if he didn't call them that, he cared. Later he goes on to prove just that, choosing Alice and the MC over Power. (See the whole Klaus affair.) Once Ella gives him his own pill, what does he do? He waits, ponders, asks our MC (whom he by this point greatly respects) his opinion on the matter. He cares. Not just about what will happen to him, but also to those he's come to finally call friends.
Does he care about Power? Yes, and greatly so.
But he's also someone with morals and a code. Saying that he would kill kids in cold blood for more power is a gross misunderstanding of his character, in all due respect.
Either way, I thank you for your time. May Shadow be with you.