Twin Flames

"What was he like when you were younger?" Jinbe asks, looking strangely intent as he stares at Ace. Ace stares back at him for a moment, before leaning his head back against the cell wall and smiling. Memories of him, Luffy, and Sabo running through the forest flash before his eyes, and nostalgia fills him. The months that the three of them spent together are Ace's most treasured memories.

He grins, shaking his head and chuckling as he says, "Well, I guess if I'm going to talk about him as a kid, I should talk about my twin first."

(Or: Ace calls Sabo his twin while in Impel Down and consequences happen.)