Modus Operandi: This player type might spend time experimenting with all the wonderful, random things a GTA title has to offer, but his or her main focus is always on taking the missions that will advance the story. How will Tommy Vercetti pay back the Forellis? Will C.J. ever be free from the oppressive yoke of Officer Tenpenny? It's these questions that pull Storytellers from high-speed chase to grueling firefight, and everything else can pretty much go to hell. Sure, it was pretty awesome when they accidentally flipped their Stinger off the edge of a ramp and sent it plowing into a frightened crowd, but what kept them coming back was the promise of another snippet of story - and new areas to go berserk in.
Won't be caught dead: Wasting precious hours fiddling with taxi or vigilante "missions." If it doesn't result in a new cutscene or open up new areas, it's just not worth the effort.
True Identity: Storytellers have usually spent their formative gaming years playing point-and-click adventures and Japanese RPGs (or, y'know, reading); for them, it's a good story that drives gameplay, and not vice-versa. For these players, a game is "finished" once the story's run its course - they might come back later for some bonus high-speed craziness, or to hear a bit of dialogue that they missed the first time through, but once they put the game back on the shelf, it's not likely to come back down anytime soon. Multiplayer? Meh. It's all about holing up in a dark room and vicariously experiencing someone else's fictional life, and anything else is just bonus material.
These are also the players who'll buy GTA IV on the 360 just because it's the only way to get the expanded content. A story's not complete if there's a chapter you haven't seen, after all.
Often heard saying: "You never played enough missions to get out of Los Santos? WHAT THE HELL IS WRONG WITH YOU!?"