Because you like Alistair in Dragon Age Series
A believer in the pursuit of justice, Garrus Vakarian hates it when bad guys slip through the cracks of the bureaucratic justice system. See them in Mass Effect.
It's hard enough fighting a war. But it's worse for Commander Shepard, knowing no matter how hard you try, you can't save them all. See them in Mass Effect.
An assassin with supernatural gifts, Corvo Attano is the last guy you should frame for murder. See them in Dishonored.
Wei Shen is an undercover cop on a mission for justice (or at least vengeance). See them in Sleeping Dogs.
A powerful dragon-hunting warrior, Dovahkiin is destined for great things. See them in The Elder Scrolls V: Skyrim.
A jaded skeptic who only wants to get paid, Garrett becomes involved in bigger struggles that force him to be less self-serving. See them in Thief.
Red doesn't like to explain herself. She wants her work to do the talking. See them in Transistor.
Stuck somewhere between life and death, Talion is motivated by one thing only: vengeance. See them in Middle-earth: Shadow of Mordor.
Sarah Kerrigan is pretty much the Queen Bitch of the Universe. See them in StarCraft .