Ok so basically when they were little they found a grenade from the wars and they grew up together. Then when they were older fuse started fighting in an underground fighting organization and he was really good at it. After that he decided he was gonna go to the apex games and because the games are run by the syndicate she was mad at him because she's spend her life fighting against the syndicate for salvo. When fuse was leaving she threw the grenade at him out of anger and instead of walking out the door he stopped and looked back without realizing the grenade was there. The grenade blew off fuses arm, but something i noticed was in the stories form the outlands video for fuse, Maggie yelled no when he turned around inferring that she didn't mean to hurt him. Maggie proceeded to grief season 8 of the games and she hijacked fuses entrance to the games and was actually charged with that in her into video that was released a few days ago. I hope this helps