After gaining notoriety on his reservation due to saving the girl, John decided he didn’t want to stay idle and, lying about his age, enlisted in the US Marines for a two-year tour of duty. There John, who was an outcast and loner during his formative years, found a sense of purpose and a camaraderie with his follow soldiers.
Attaining the rank of corporal, John earned a number of medals, including one for rescuing a helicopter pilot downed in the Caribbean Sea by lightning while traveling to Guantanamo. It was during this mission that John witnessed what he believed to be his totem: a great bird of lightning in the sky.
Once John returned home from his tours, he found himself restless and withdrawn, depressed and bored due to not using his mutant abilities for good. It wasn’t long though before he found himself approached by Professor Charles Xavier —who’d offer the reluctant-to-join John a spot in a new version of the X-Men. It’s there that John would take on the code name Thunderbird, based on the vision he saw in the stormy Caribbean sky.
On top of being a skilled hunter, tracker, and fighter (in both hand-to-hand and small arms combat), Thunderbird’s muscle tissue is three times as dense as that of a normal human’s, distributed in such a way as to give him massive shoulders, arms, and thighs.