How you caught his attention:
When you saved him from the bullies in the real world, when you both made an eye contact his heart started to beat faster he thank you so many times and you said it was nothing after that encounter he never seen you again
When he met you again:
He was very happy to see you again of course he didn't make it obviously
After the game he kidnapped you and bring you to the beach
It took you a minute after you recognize him you we're very shock that the dimwit you saved in the real world are now looking at you like a predator and you are his prey
When he became a Yandere:
He kills the guy's who tries to flirt with you whoever guy stare at you he shot them straight in the head
He would always be around you whenever you go even the games he will sacrifice everyone just to protect you
How he got jealous?
He kills the guy who tries to touch you and lock you up in his room
Would he kill for you?
Definitely yes, heck he could even burn the beach just for you
Does he let you wear his clothes?
Yes he would let you wear his clothes everytime sometimes he forced you to wear it so that everyone in the beach knows your his