I use so many characters, people have a hard time figuring out who my "main" is. Some main more than one character, some cycle through so many, and some just stick with one. I fulfill the second criteria.
Some of the characters I use represent people who have inspired me with their strategies so I could improve my own game. Examples of this would be how SHORYUKEN represents my Sub-Zero, marvaz represents my Liu Kang, Pig of the Hut represents my Cyber Sub-Zero, Mr. Mileena represents my Kitana...I think you get the idea. But rather than discuss how I main multiple characters, I'll just talk about my primary character:
Raiden.
His story as a character fascinates me in ways I can't quite explain. He represents the logical portion of my personality through his unending wisdom. Originally I was inspired to use him by...a friend whom I had a regrettable fallout with (this happened back when I played MKDC), I kept going with the flow, and I was startled by how well I connected with Raiden. People may call his playstyle "noobish" all because of his teleport, but this goes to show a lack of understanding about him. It takes more than a teleport to be a master of space control like how Raiden is...much tougher to play with him than what people realize. No matter which Mortal Kombat I play, you can always count on the Thunder God lurking in my roster.