This works on any major faction and is very much a major exploit. So if you don`t like a HUGE amount of cheese then you should not read this.
Fill up a faction`s prison by ether waiting for a big battle or leading a bunch of bandits to the gates.
Get 2 bandits with bounties, the amount does not matter.
Turn in one bounty to fill up the warden`s arms.
Tun in the second bounty, the warden will not be able to take it and it will give you a + to relations but will only give you cats once. Turn in the second bounty over and over again raising relations by 2 or so. After doing this 50 (Less if bounty is higher.) times you will be allied with the faction.
Step Five, Profit
I hope this guide was of some help. This is very OP! And i am very sorry if i have made anybody feel as if their progress in-game was meaningless.