Morrowind:Rabinna's Inner Beauty

Quick Walkthrough
# Talk to Relam Arinith at Fatleg's Drop Off in Hla Oad about Rabinna.
# Lead Rabinna to Vorar Helas in Balmora.
# Either defend Rabinna or let Vorar Helas kill her.

Detailed Walkthrough
Speak with Relam Arinith in the basement of Fatleg's Drop Off in Hla Oad. He needs a slave named Rabinna delivered to Vorar Helas in Balmora. Evidently the actual slave is not important, but what she carries is... illegal drugs of some form. Along the way to Balmora, you can talk to Rabinna (if you raise her disposition to 50) to determine that you have a choice of what happens in the quest.

If you decide to deliver Rabinna to Vorar Helas on the east side of Balmora, he will attack Rabinna immediately (to get the drugs). Once she is dead, you can talk to him to receive a reward of 400 gold and a magic ring. If Rabinna dies on the trip and you rescue the Moon Sugar and deliver that to Vorar Helas, you'll just get 200 gold and no ring.

Alternatively, you can help Rabinna kill Vorar Helas (or just avoid him entirely), and deliver her to Im-Kilaya at the Argonian Mission in Ebonheart. The easiest way is to hop on the boat in Hla Oad. Once you have delivered her to the Argonian Mission, you can talk to Im-Kilaya to receive a 400 gold reward and a 10 point boost in disposition with the Twin Lamps.

Finally, you can speak with Relam Arinith after freeing Rabinna. If Vorar Helas is dead, he will consider the matter resolved. If Vorar Helas is still alive, then Relam Arinith will attack you.

Notes
It is possible to receive both rewards from Vorar Helas and Im-Kilaya. Take Rabinna to Vorar Helas and hand her over to receive the first reward, then aid her in killing him, loot his corpse and take her to the Argonian Mission in Ebonheart to receive the second.
:*If you enter through the back door so Vorar Helas doesn't see you, the Journal will still update as if he had immediately attacked and killed Rabinna. He won't attack her since neither he nor Rabinna will move where they can see each other. If you talk to him, he will give you the gold and ring. Rabinna will no longer follow you or offer any useful dialogue, but if you taunt and kill Vorar Helas, he will have 20 units of Moon Sugar on his corpse as if he had killed and gutted Rabinna. Then she will thank you for killing him and ask you to take her to Im-Kilaya.
If you kill Vorar Helas at any time, you can loot his corpse for 400 gold, the key to his house, and the ring that you would have received from him as a reward.
If you are unable to raise Rabinna's disposition above 50, you will need to kill Vorar Helas to ease her fear so she will talk to you about taking her to the Argonian Mission. 
You can complete the quest by taking her to the Mission without ever talking to her or seeing Vorar Helas. Rabinna will thank you on arrival and Im-Kilaya will reward you.
The moon sugar you specifically obtain from Rabinna after killing her or looting her corpse is not required to complete the quest. Any such moon sugar will do, as long as you have at least ten units thereof. 
You can complete the quest without accepting Relam Arinith's offer to deliver the slave. Talking to Rabinna after refusing Relam's offer will open up her dialogue to have her follow you.

Bugs
 

Quest Stages