So, I'm a little fuzzy what constitutes the regular RPG as it's such a banket term, let's see if I got this...
So there's me, who always plays the equivilant of the Knight class, so I'll be in close-proximity to enemies.
Isaac Clarke (DS2 iteration) because he knows how to get shit done that needs doing, and isn't afraid to literally bust a few heads to do it. Plus, delving into his mind in a non-hostile way would be quite interesting. I might be able to help him get over some of his mental baggage as well. Hilariously enough, he will be the most "normal" person on this team, seeing as how he is literally just a man thrust into horrible circumstances, so he'll probably be the one I'll be able to relate to the most.
DOG from Half-Life 2 (Episode 2, to be precise).
A rhino-sized robot with the attitude of a (highly intelligent) loyal pet whose sole purpose in existence is to defend me from harm? Yes please. Especially since he can throw a few tons of steel through the air like it was made of paper mach'e.
Eleanor Lamb from Bioshock 2 (Big Sister)
Dat Harpoon...she's basically the equivilant of a Steampunk Battlemage. She contains not only the strongest versions of Plasmids ever shown (exploding fireballs with Incinerate and hurling huge chunks of concrete with Telekenesis), but she's also got crazy ninja skills and the intelligence of the smartest people in Rapture, and is shown multiple times to be even more powerful than her father (Delta/You). Plus she's kinda hot, and legal. It's a no-brainer.
Yuna from FFX
Only because
somebody is going to need to be casting Life a lot to resurrect me when my dumb ass charges something fifty feet taller than me with reckless, melee-attacker abandon. Gonna need some party healing as well. At least Yuna somewhat makes up for the stereotypical "healing only" White Mage with her Aeons and her ability to learn quite powerful Black Magic.
Odahviing from Skyrim
I wasn't going to choose anybody from the Bethesda games, but come on.
He's a fucking dragon.