Aria: Blue Suns

Aria T'Loak has a proposition for Shepard.

Acquisition
Speak to Aria inside the club Purgatory on the Citadel.

Walkthrough
First, meet with Darner Vosque in the loading bay area of the Citadel. Vosque will tell you that he wants General Oraka dead in order to pledge his allegiance to Aria (as well as some of that "blue ass" to seal the deal). If you choose the Paragon option not to kill Oraka, but rather to try and persuade him to back off the Blue Suns, you will find him in the lower part of the Commons area.

General Oraka will tell you that he needs you to secure high grade weapons if he is to lay off the Blue Suns, that way the Citadel can still be prepared for the eventual Reaper attack. Further down in the Common area, you will find a Salarian named Kannik who tells you that he will sell to C-sec as long as you find rare artifacts to give to him.

You will find the artifact in Kite's Nest on a planet in the Vular system. Return to the merchant and then talk to Oraka. You've got the Blue Suns.