This is my take on the factions in the game, based off of the Two Cows Metaphor, often used to satirize economic or political ideologies.
Stormcloaks
You have two cows. You put one in a cramped compartment, and get mad when it doesn't give you any milk.
Imperials
You have two cows. Someone tries to steal them from you, and you get in a big fight over it. It's a stalemate, but you give him your cows anyway. Now all the cows hate you.
Forsworn
You have two cows. You took them from someone else a long time ago. It was so long ago that you can say that they were always your cows. Most people believe you, but they hate you anyway.
Thalmor
You have two cows, and they hate you. You go to steal someone else's two cows, and you get in a big fight over it. It's a stalemate, but he gives you his cows anyway. Now all the cows hate both of you.
Thieves' Guild
You have two cows. You stole them. Nobody cares though, because you bribes them with the cows' milk.
Dark Brotherhood
You had two cows, but you killed them. People give you milk to kill other people's cows.
College of Winterhold
You have two cows. Nobody wants anything to do with your cows, but pay good money for the milk.
The Companions
You have two cows. Every cow wants to be your cow. You genetically modify your best cows.
Bards' College
You have two cows and you can sing. But nobody cares.
Feel free to add your own, or your own take on these!