Sometimes it's better not to ask where inspiration comes from. If you can call it that.
Sometime after the events of Blood Gulch…
Grif has long since said his goodbyes to the empty box canyon known as Blood Gulch. He said good riddance and went off, to explore the galaxy rather lazily and to get as far away from Blood Gulch as possible. Why would he explore the galaxy? Because he's by himself and that way he has to do next to nothing and there's no old guy in red armor shouting at him and making several failed attempts at his life a day. He's even been to Sidewinder, but didn't stay too long, claiming it was cold (which is impossible for him to feel because of the MJOLNIR armor).
Anyways, a few years of wandering around has made him lazy. I mean lazier. His combat reflexes (if he had any to begin with) have gotten sloppy. So one day while he's out, he's surprised to see a SPARTAN craft just like his. Come to find out, it's an old rival, Caboose of the Blue Team. Caboose, never too brilliant, figures that somehow if he kills Grif then maybe just maybe Church will like him even more. So he begins firing upon unsuspecting Grif. Thus begins a long, galaxies spanning chase.
After about a year of dodging several attacks, most which can't be called actual attacks, from Caboose, finally Grif gets hit. His ship gets severely damaged and he crashes on a planet in the desert area. Fortunately he's not hurt in the crash. Unfortunately, his armor is damaged in the crash beyond self repair and he crash landed on top of some poor soul. Upon removing himself from his armor and the crash site, he notices that the sky has gotten very cloudy. "Oh man, I hope this isn't gonna require any work." He sighs then shouts "Son of a bitch!" as a giant dragon appears in the sky.
"What is your wish, SPARTAN?" Grif looks around, and then looks back at the dragon.
"A talking dragon? I dunno sounds kinda fishy. Is that you Caboose? Wait it can't be he's not smart enough to think up a plan. I wish I had the power to get rid of that guy…"
"Done!" All of a sudden Grif gets a pain in his ass. Looking back, he's is very shocked to see a full tail swishing from his backside.
"Oh you have got to be kidding me… I hope no one's around to see this…" As he says that, he hears a loud noise and spots Caboose's ship on the horizon. "Oh man, I gotta fight this guy without any weapons? Should be a challenge. Wait that's not something I'd say. Why don't I wanna run away?" Grif ponders this for a moment, before realizing that maybe that dragon did more than give him a tail. "What is this energy I feel inside of me…"