Garp Secretly Raised Roger's Son At Rouge's Dying Request
Status: confirmed · Technique: dialogue-from-dead-character, prop-tell
The seed
Dying flashback (Ch. 550 p. 19): Portgaz D. Rouge hands her newborn to Garp — “My unborn child is innocent, Garp! Take care of my son!” The Navy’s greatest officer, Roger’s chief pursuer, secretly becomes the foster-guardian of Roger’s son.
The payoff
The Sengoku broadcast in the same chapter makes the Garp-as-Ace’s-guardian fact public alongside Ace’s Roger parentage; the on-page dying-request establishes the foster-guardian relationship within the window.