Helping the Consort on the Citadel in Mass Effect: Legendary Edition isn't something even hardcore completionists always feel compelled to do. There are no monetary rewards. She doesn't give Shepard a weapon, armor, or even so much as a mod. In fact, her only immediate rewards are words (no, really), a steamy scene (for those who want more than words), and a worthless trinket that she doesn't know how to use.
It gets worse. The other two have some low levels of story value, but the trinket doesn't even have so much as a quest tied to it. Players can complete the game 100% and never find out what the trinket does. So why bother at all? Because the trinket, without much dispute, unlocks the single largest piece of lore in the entire game. It reveals something that players can learn about once and then never again.
Getting The Trinket
The first step is simple: Head to the consort's office in the Presidium. After initially being rejected from a meeting with the asari consort, the receptionist will then ask Shepard to go and see Sha'ira upstairs. In order to acquire the trinket, her mission must be accepted.
The first task is to see General Septimus in Chora's Den. He'll be getting wasted and can't be helped unless Shepard has a certain amount of paragon or renegade persuasion levels. He's not going anywhere, so if Shepard can't convince him now, just make a mental note of his location and remember to come back later.
Don't go to Sha'ira just yet. After that, Septimus will admit that he's responsible for a data leak that was erroneously blamed on Sha'ira. Go and see Xeltan in the elcor and volus embassy to correct the mistake.
After fixing the issue with both of the individuals that hated her, Sha'ira will thank Shepard and, among other things, give him a trinket that she doesn't know how to use. There is no marked quest for it, so this often remains a gigantic mystery except for those who know exactly where to go.
Solving The Mystery
Hop aboard the Normandy and go to Eletania, which is in the Hercules System of the Attican Beta Cluster. Upon landing, note the question mark in the lower lefthand corner of the map. It's surrounded by mountains, so don't be afraid to crank up the turbo engines on the Mako.
Upon arrival, players will find a prothean ruin unlike any other previous discovered ruins; in fact, this is not a ruin at all. It's a fully-intact beacon! Players will need somebody with some tech abilities to "recover" the Mysterious Globe. After playing the minigame, interact with the object one more time.
Unlike the beacon on Eden Prime, this one does not explode upon use and is not distorted. Shepard will learn that the protheans had discovered the earliest remnants of human life. Not only did the protheans know about the humans, they actually spent time abducting them, tagging them, and monitoring their progress.
Shepard gets to see these abductions firsthand from the point of view of the tagged individual. Though the whole scene plays out through text, it's one of the single most shocking revelations in the entire trilogy.