The reader suddenly appears in Amazon Lily and is pulled into Luffy's mess, when forced to fight the Medusa sisters, he runs around in a panic, scared for his life. But when he is nearly crushed, he covers completely in Armament Haki and resists the attack. When Luffy goes to save Ace at Impel Down, the reader is forced to stay cause of his lack of experience, but uses this opportunity to get the hang of his Haki. He hides on Hancock's ship and when Luffy and everyone arrive at Marineford, he made himself known and showed a unique skill he suddenly developed, taking in the strength of the blows taken and releasing the pure concentrated force. Ace still dies, but the reader uses Haki to keep his wound closed and force restart his body, and brings him back to life, but he lost his devil fruit powers, and the reader believes it's best that the world believes he's dead and that Ace go into hiding. News spread about the Battle, and word of a boy who has powerful and great control of Haki spreads to the Big Momma Pirates.

Haki:
Armament(pretty much impenetrable, and absorb blows, and release the force at a high multitude(can hurt him like Deku using one for all))

Perception(trained highly during two year training, where luffy used the reader as a punching bag so to increase the readers durability and use of both Armament and perception(but sensing the attacks, but not blocking or dodging them), sometimes a headache and a glimpse to the future)

Conquer(powerful)

Please use, Please~