"Greetings. Perhaps you can be of some help to me. There are sensitive matters to attend to."
Sensitive matters:"The great Daedra Mephala has given me information that must be acted on. If you would be willing to work with me, I'm certain Mephala would be grateful"
I would like to to help:"Excellent. There is a member of our brotherhood living in Balmora, Balyn Omavel. He has been...freelancing, if you will. This is unacceptable, and he must be removed. Unfortunately, his brother is a rather important member of our brotherhood, so it would be difficult to bring it to the attention of the others. Use this poison in his food. It acts swiftly, as should you."
I do not wish to be involved."I understand. I trust you will speak to no one about this. Mephala would be most displeased, and her reach is great."
"You have been given your task, %PCName. You should complete it before Mephala is angered.
"Unfortunately, you were seen going into the house of Balyn Omavel. Mephala is not pleased. No matter. I will find someone more competent to complete this task. Goodbye.
You've killed him in a way other than was described? That was unwise. Mephala is not pleased. Leave here.
Well done. Mephala wishes to speak to you directly. This is a great honor for you. Approach her altar.