The caption could be either of two very feasible options.
#1: Tucker is graciously visiting his brother, providing moral support, encouragement, and entertainment while he is held captive behind bars. He is patting him on the back to say, "It's okay, little brother. I've been where you are. I'll stay with you until Mom rescues you, or until you fall asleep, because I love you so."
#2: Tucker is gloating about his ability to walk, and showing Tyler that there are some benefits to being older and free to be mobile. He is patting him on the back to say, "Someday, you too will be on two feet and will have freedom. But not today. Bet you wish you were me."