Bowen Brant is an NPC based in Caer-Konig in Icewind Dale. He gives you details on who the Ten-Towns are and also how contracts work.
Conversations With Bowen Brant:
Tell me about the Ten-Towners.
We are the people of Icewind Dale, the descendants of the pioneers who carved a home out of these frozen lands. Although each of the Ten-Towns is an independent entity, we band together when threatened by outsiders. That's just what we did when the mad wizard Akar Kessell led his armies against us, and that's what we're doing now in the face of this invasion of Southern Wizards!
Dam the Arcane Brotherhood! Akar Kessell himself was an Arcane Brotherhood member, as was Valindra Shadowmantle! Does that sound like a group that has anyone's best interests in mind?
How do contracts work?
It's simple really. You sign a temporary contract with me and our Ten-Towns agents will assign you certain tasks for you to complete. While you're under contract with the Ten-Towns you'll be unable to complete tasks for the Arcane Brotherhood.
It may be that holding such a contract will bring you into conflict with those working for the other faction. Feel free to bust their skulls as far as I'm concerned, but that will be up to you.
Contract Facts: -Signing a contract with either the Arcane Brotherhood or the ten-towns will set your faction for PvP (all PvP participation is strictly voluntary). -All contracts are temporary and will expire after a character has been logged out for more than 12 hours. After this, talk to Bowen Brant to retake this contract or Anara the Cerulean to work with the Arcane Brotherhood. -You may break your contract at any time by talking to your faction leader.