1. Don't be afraid of everyone gunning after you.
2. Choose a cabal of your liking (like any)
3. Roleplay their friend - take part in their raids/reraids/fights.

This way everyone will see you as their lackey, and you'll get the action you want and RP. You'll just not get the cabal powers, but who needs those if you're assassin with Nage Waza edge?

The best way for that is Empire. Become their lackey (they LOVE those), get your alignment changed (that'll happen quite quickly if you play an ass), oath - hello you're in a cabal.