Continuity mistake: After busting out of the cake and killing the two Lunar Max guards, Boris' hand creature goes to free him. It first blasts spikes at the shackles on his legs and busts them, then begins climbing up to work on Boris' arm piece. In the shot where his leg shackles come off, you see the spike the creature shoots at them stuck in the metal and hanging off to the side. But in the shot where his arm piece falls to the floor, these spikes have vanished from his leg shackles. (00:03:35)
Chosen answer: He saw J's father murdered by Boris. In the unaltered timeline, J says that his father wasn't around. We see this at the end and it's also why J was recruited into the Men In Black. K was keeping an eye on him the whole time.
Brad ★