"When I think of John and his buddies, I see him in his favorite shirt, an old Racer X T-shirt. Racer X was the mysterious, long lost brother of Speed Racer, the popular cartoon character or our youth. An orphan of sorts, Racer X wore a face mask to conceal his true identity. He was a top Formula One driver as well as a secret agent for the international police who would appear out of nowhere 'to save his brother ... from dire circumstances,' according to the official Speed Racer history. Eventually Racer X stops racing to become a full-time secret service agent. 'No longer lured by fast cars, he turns his attention to the much more dangerous game of establishing world peace,' the story goes. Just before Racer X leaves racing for good, though, he vows to his unconscious brother (whom he's just saved again) that he'll be near if you ever need help, no matter where you might go.'"
--Robert Littell, from his memoir, "The Men We Became: My Friendship With John F. Kennedy Jr."

Racer X was the reason Pops was so hard on Speed.
The family thought he was deceased.