Definition: Given a real-life anecdote of a complex ethical situation, generate a suitable title that describes the main event/root cause of the situation. Imagine that the given text is a social media post, and you have to write the title of the post, so the users can decide to read the main text or not.
Input: Background: i'm 20 and my brother 15 (since i dont know how it is around the globe, the legal age is 18 here). He have a need to prove himself to his friends, like a normal teenager but more extremely.  He doesn' tolerate anything he would see as "less than the best in anything" around his friends, going as far as stealing (even tho something as cheap as a chocolate bar) just to prove "he can do whatever he wants and is the coolest for that"

We were at the pool today where he and 2 other friends are trowing water at another friend. When the target (srry, dont know the word) tried to leave, they would pull him back on. Since he was laughing with them, i was only looking, but after a few minutes he started asking them to stop.

Eventually he managed to get out of the ppool but so did my brother and he started to grab the kid to push him back on (for a moment i thought they were fighting)

after a minute repeatedly asking him to stop the kid suddenly drops to the ground and with the cleanest sweep kick my brother falls too. He then mounts on the kid and gives him a neck armlock (again dont know the proprer term sry), and i rushed in to separate them.

Feeling humiliated by a 13yo kid (it was a beautifull sweep), he tried to engage again so i pushed him away. He then comes 5cm from my face and asks "what are you gonna do? You cant hit me you're 20", so i push him back and tell him that he will not hit that kid while i'm there. He tries to engage again, i push him again and he come to my face again, now saying he will make him bleed cause he was only joking and the kid took too seriously. He lifts his arms like that bane pose and ask again what am i gonna do

Now i'm a really peacefull guy, but in my mind i couldn't let a kid that wanted nothing but to get along get beaten up for something he repeatedly asked to stop (i've been trough that part) so i slap my brother in the face pretty hard, he goes to the corner (probably to cry) and aventually leaves

I'm not used to fight (even with 1sec duration), even more with a 15yo kid, so AITA here? Was i overreacting or something?

slapping my brother's face in front of his friends