I don't own Gundam Wing and am not making any money off this.
When Duo was young, and he'd lived and learned on the streets, his favorite thing was stealing enough food to calm the hunger pains. He dreamed of a big house and clean clothing.
When Duo lived in the church, his favorite thing was warm baths and Sister Helen braiding his hair. He dreamed of a real family and no more fear.
When Duo fought and killed and was hurt in the war, his favorite things were fresh bandages and waking up in a real bed in a safe house and breakfast with his family.
When Duo joined the preventors... well, his favorite thing was when he quit. He dreamed of a life where he wasn't alone.
When Duo wakes up in the morning he looks back on his favorite things and smiles at Heero and curls deeper into his arms and decides that he's done wishing.