More Hero than Thou / More Expendable Than You: Often his reasoning is that he’s just another Glass Cannon, Misty can theoretically resurrect him, and she’d be safer with Ash or one of the other less-squishy folk protecting her than if the mage was protecting her. He makes several of these sacrifices, but being a lucky bastard, he manages to survive anyway.
Undying Loyalty: He is fiercely loyal to his friends. Since they need each other in order to survive (especially since he relies on Ash to protect him and Misty to heal him), this is justified.
Write Who You Know: The reason he’s a fire mage is not only because it works for the plot, but because fire mage was, at the time, the only class-spec combination the author knew well enough to write as a main character.
Fake Defector: First she acts as a double agent pretending to be Scourge, then she is pretty much forced into a Shoot Your Mate situation, making it look like she really has gone to the dark side.
Incorruptible Pure Pureness: Again, it comes with being a paladin. Or so it seems. She comes dangerously close to corruption multiple times.
Jeanne d'Archétype: Misty is a normal girl in her own world, but becomes an armored, sword-wielding holy warrior when she gets the Call to Adventure. She later leads at least one charge into combat. Sound familiar?
The Chick: Jessie has very little personal usefulness before or after outland (where her knowledge of demons is important), though she has her moments such as when she saved James from a ghoul, and when she befriended Sylvanas and the undead Forsaken. Otherwise, she’s mostly just extra firepower.
Knife Nut: Her daggers are Poisoned Weapons, no less, and she enjoys finding ever new and creative ways to poison her enemies. Yes, this is a hero. Cross another villain stereotype off the subversion list.