Zapper looks very much like his older brother Blaster; in fact, they are considered to be identical or twins although Zapper is younger. Like Blaster, Zapper has deep blue eyes and golden-brown hair. He wears a leather jacket with a striped t-shirt under it, along with dog tags which presumably belong to Blaster.
Not much is revealed in the games about Zapper's personality, other than the obvious conclusion that he loves his brother and is brave enough to fight in Blaster's stead. The official Sonic Wings website suggests that Zapper may be calmer and quieter than Blaster, but states that his character was never really developed.
In the US version of Sonic Wings Assault, the character Hawk bears a strong resemblance to both Blaster and Zapper. Therefore, one fan theory suggests that Hawk is intended to be Zapper, finally getting to fly for Project Blue on his own.
Zapper vows to take over the mission for Blaster after the elder Keaton appears to have perished in the final boss battle. Therefore, the second run of the game is completed using Zapper instead of Blaster, but the two characters' planes and attacks are identical.
In its updates on previous games' characters, the Sonic Wings 3 strategy guide asks, "What's going on with the younger of the identical brothers?" but doesn't offer any answers. Video System's website suggests that perhaps Zapper went back to a normal life after Blaster returned.
The ending from Sonic Wings is reenacted in Special in single-player mode if the player uses Blaster Keaton (not Mecha-Keaton) and chooses the game route which leads to the boss battle with Pandora. After the boss battle, Pandora's ship wrecks Keaton's plane, seeming to kill him, and Blaster's younger brother is again shown vowing to fight on in Blaster's place. This ending is not included in Sonic Wings Limited, as Keaton is only playable in his robot form.