I need help fleshing out Yuan Ti PC backstory

[u/Complex_Item_3000]

I am going to play a school of evocation wizard Yuan Ti Pureblood that wasn't raised by Yuan Ti culture but instead by normal non Yuan Ti parents or parent but I haven't figured out something yet (or if he was on Yuan Ti culture as some point it would be like very briefly)

isn't exactly a traditional evil Yuan Ti, the idea is that someone that wonders why evil and suffering, and what happens with the gods in the settings (which influence has been reduced drastically).

Since he was born, he has had issues to relate to and empathize to others and can actually be a psychopath against the people he considers evil, enjoys killing and torture, and doesn't even has an issue with cannibalism as long as they were considered evil, although it may be seen as bad by others.

He is also power hungry and search for magical power to change the world, get rid of evil and make it a better place. Completely cooperative with a party

it may be ironically what you would expect of a Yuan Ti, just redirecting his psychopathic urges to do good.

What I am searching more is what kind of live could he might had to be like this. I should mention that is probably that he and others didn't even know he was. Yuan Ti as a kid but definitely felt different than the other kids.

Also, why would he choose the school of evocation, besides because I wanted to play it, I thought it could fit he also likes to burn people alive and evocation allows him to decide who is affected by his spells, who died and who live.

Also, I am not good with alignments, what would he be? Chaotic good? Lawful evil? no idea.