Etarn Tiron is a turian living and working on the Citadel. He is the shopkeeper at Rodam Expeditions.
If Commander Shepard elected to save the original Council during Saren's assault on the Citadel in 2183, Tiron expresses great admiration towards Shepard and is cordial. If asked about the store's wares, Tiron wholeheartedly describes taking down a shatha, a dangerous game animal, as an experience (not a vacation) that can only be done with Rodam Expeditions gear.
Shepard can record an advertisement for Tiron, gaining a discount; he also says that he would name his first-born after Shepard if asked to. Alternatively, Tiron can be persuaded to sponsor Shepard's mission in the Terminus Systems. Happy to support anyone hunting mercenaries and geth, Tiron gives the Commander a discount, and wants them to bring him back a geth head to turn into a desk lamp.
If Shepard let the original Council perish, Tiron is visibly angry at Shepard and snipes the Commander for being prejudiced against alien species. He specifically calls humans Kinslayers when Admiral Hackett let the Council die, or questions why human scavengers would even need guns when they only strike when the prey is weak. With some persuasion, however, Shepard can convince the resentful turian to give them a discount by impressing him with their ability to kill the 'scum' of the Terminus Systems. However, there is a caveat: Tiron will deny the existence of the discount if anyone asks.