Rather than fight, Kuma asks Nami whether “Monkey D. Luffy has an older brother”; on her confirming Ace he says only “I see. So it’s true,” and refuses to explain (“is none of your concern”) (p. 18). A sitting Warlord taking targeted interest in a rookie’s bloodline — with no stated reason — is a deliberate negative-space tell: the why (and for whom Kuma is really acting) is the planted question.
The interest deepens at Ch. 485: the cryptic bloodline-question is answered for the reader — Kuma knows not just Luffy’s brother but his father, and treats the paternity as grounds for mercy rather than a kill order. (Folds in the reader’s 0485 seed “Kuma Knows Luffy Is Dragon’s Son / Secret Allegiance”.)
The payoff
(The deeper “defied fate to save the modern Joy Boy” layer of Kuma’s motive lands far later and is forward of this window.)
Why this matters
Negative-space + chekhov-explicit: the unexplained interest, not a fight, is the tell — Oda plants the motive question of a Warlord who will repeatedly, inexplicably intervene around the Straw Hats.
(The dialogue-from-dead-character technique tag is used loosely for the “cryptic line from a figure whose true role is hidden” pattern; the primary techniques are negative-space + chekhov-explicit.)