But what if he didn't want to fight back because he didn't wanna make his mom sad instead?
that would be hella stupid and out of character, it's been shown throughout the series that he's still an objectively bad person just like his father; he's been raised since a kid to become a murderer and a killer. he just cares for his mom. his mom only came in because he was taking a while to come on in. if he had just beaten up everyone or just ignored them and come on in on time she wouldn't have even known there was a fight.
Out of character? Hes a two faced. Evil behind her back but kind in front of her face. It's not out of character that's who he is and that's how he has been acting this whole time. Hes been taking the beating ever since the beginning, the main girl even talked about how the old step mother used to bully him at parties. I mean maybe he is doing it to gain her pity but maybe he isn't and just doesnt wanna disappoint her cause to her hes "a good and innocent kid" and he knows she thinks that way about him.
im pretty sure she knows hes already messed up, she just wants to get closer to him so he doesnt kill her. im pretty sure he doesnt need to get beaten up in order to get her attention; and him being beat up should in fact ruin his family name since his family has this entire reputation of being intirely evil. i don't know how accurate the plot is going to evolve from the pre-established facts and history that it takes its inspiration from via setting, but him getting beat up would a) tarnish his family's name (which just means he would be tortured more to become less weak and more attempts would be made on his life as he's now perceived as a weak kid) and b) wouldn't necessarily give him any more attention than him just feigning being sick like his father. once again, i don't know how they will write it, but based on all the previously set up plot lines and the general royal history and stereotypes this story takes inspiration from, him being beat up on purpose is hella stupid. but i don't really think that the author would bother going into the politics that him being beat up would actually warrent.
Ain purposefully let himself be beat up so he could get more attention; let's not romanticize it or call it cute, that's hella messed up. ain and his dad are both objectively bad people. let;s not forget that.