(I don't know why, but this is my thought process right now. I have a scenario in my head that goes like this.)

Jack left a while ago to go see the world, he hadn't come back to Neo Domino for a few years and when he did he decided to burst into Yusei's place first to see him again. Yet when he did he was told to quite down as next to Yusei with their head on his lap, a small child that looked like Jack was asleep. How will Jack react?

(Again, Just my thought process. Yusei ended up having Jack's child and never told him!)