Disturbing scene about a puppy being killed and something sad / cruel with the mother afterwards. Will not give details for triggering reasons. Do not read if these kinds of things trigger you.
The protagonist. He's raised in horrible conditions without a single show of love and care from any adult around him, and he ends up becoming a horrible human being.
Considering the circumstances, kind of? There's no actual sexual content including a minor, but the way some minors are presented from the protagonist's POV, it does seem like he (not the book) thinks of them as objects to satisfy his wants.