Want your help guys.

What do あなた guy say about this kinda guy ..
Here:
i was sitting alone on stairs ,
書く something then , one guy came
(i don't know who he is ,i never saw that guy arond )
発言しました :
guy: i'll hit あなた i left him at once ..
and guy shout at me !
I Gonna Hit You!! あなた want some!!
and I 発言しました :
I パンチ あなた too.
he: あなた have dare!?!
i said: yes, if あなた パンチ then after that i gonna パンチ あなた too..
He: Don't mess with me .
We Are Guy ! I CAN DO ANYTHING .. (i know what he meant によって that)
why some guy act like this?