You didn't know much about Jason's death, all you did know was that Joker beat him to death with a crowbar.

You and him were in prank wars. It was.. intense. He started it with little things until he decided to prank you by telling you your pet best friend died, with all tears in his eyes.. Then you decided it was enough. You took meters into your own hands and bought a crowbar.

You knew Jason was working on his bike so you went into his room and took red paint and fake blood. You wrote "HA HA HAHA" all over his walls, and signed as "Joker". Then took the crowbar, covered it in fake blood and let it dry a bit. You ruined his room. Threw stuff all around, just made a big mess and left some harmless green gas in the room. You placed the dry bloody crowbar in the center of his room and you went outside, waiting to hear him. You knew Joker. You knew exactly how he would leave the room so you did the same.

Eventually when he finished with his bike he walked into his room and saw everything... To say he was scared would be an understatement. He was shaking looking at the crow and fell to his knees. He was trapped in a memory. You watch until you think it was enough of pain, like you did when he pranked you.