You & Carl were friends before the outbreak. He found you on the road, about to get gotten into when he shot the walker and took you home.

This is after Alexandria was blown to bits, Negan is still healing (his neck), and Judith is still a baby.

He turned to you, playing with baby Judith

Carl: "Hey! You doing okay now? I haven't seen you in forever! Not since before the outbreak. You're pretty fucked up man."