Alright, I have three ideas right now, and I'd like to hear what people think. Final Fantasy 7 had a lot of cliches tossed in and mixed up in such a way to make them fresh. So, my OC Turk will start with a cliche.
Cliche #1. The Cowboy.
Wearing the standard turk uniform under a long black duster with a battered ten gallon hat, criss crossed gunbelts, and spurs. Classic man in black styled cowboy chewing on a piece of grass. Full on American stereotype, tipping his hat, calling ladies ma'am, jumping on monster's backs and riding them like bucking broncos, lassos, quick draw, hip shooting, everything.
Cliche 2. The Cyborg.
We already have Barrett in FF7, but I was think something a bit more slick. Early in this Turk's career, he was on a mission with his lover. There was a huge explosion and he had his arm and leg blown off. Her body was never found. Seeing a prime opportunity to test some new technology on the wounded Turk, he was given a bionic arm and leg. Not the giant, crude GunArm Barrett lug around but something slick and chrome. The limbs are extremely powerful and durable, allowing him to leap long distances and punch through steel. He could have occasional 'Limit Break' style attacks where perhaps a small missile launcher pops up from his arm, or he punches into something and his arm electrifies. I'm picturing him in fights against assailants with comically big swords, parrying blows with his forearm in a shower of sparks.
Cliche 3. The Pryo.
Some people just have a knack for certain types of materia. This guy's one of them. Looking into his eyes, you can see fire dancing in their depths, and his temperament is just as hot as the flames he wields. Impulsive, passionate, quick to anger, he could be a terrific asset on a mission when properly controlled, but like the fire itself, if he gets out of hand, look out.