“I don’t understand what did Alicent do to him for him to act like that towards her”

First he was raised with misogynistic ideas around him (his mother being a victim of it and a misogynist at the same time) so ofc he will look down on women. Second, yes she was the one who stood up for him when he lost his eye but she literally allowed Aegon to bully him as long as it’s not in public, at the same time. He’s also frustrated because she didn’t condone what happened to Luke and didn’t want him to be part of the green council to begin with.

Mostly and most importantly ; she is the person he loves the most. Love = weakness to him. Hence the fact that he’s the only main character with zero love interest btw (for the moment). She’s the personification of all the feelings he can’t bare to express anymore.

“I don’t understand why he burned Aegon”

Aemond is basically a teenager (important to remember that) who is impulsive (he regrets the shit he did to luke) and has anger issues. He attacks people who hurt him and the people he loves (bc yes, he does love). He has conflicted feelings for Aegon because of all the shit he did to him. He e wants the throne not really for himself but to win the war at all costs, because his mother always told them that the family would be in danger if team black was ruling. Also to show that he is capable of great things (he claimed the biggest dragon to show that he isn’t a weak bullied kid) and that he is better than Aegon.

His brother never showed real affection towards him (him allowing Aemond to be part of the green council was pure strategy since he has Vhagar) and spent most of his life degrading him and bullying him. Y’all also forget that he is the reason he’s sexually traumatised bc he allowed him to get sexually abused. Aemond has more reasons to hate Aegon than to love him. We legit have zero scene of them being lovely brothers to each others btw.

The whole “I’m strong and nothing and nobody scares me” is just a facade. Look at the way he tried his hardest not to look at alicent (or cry but you didn’t hear that from me) when she talked to him on episode 6 bc he knows his mask would fall off. It’s a shield he uses to protect himself and to never show weakness bc he doesn’t want to be mocked and hurt anymore.