In Mass Effect 2, Tali’Zorah’s loyalty mission involves her appearing in front of the government of the quarian Migrant Fleet.
Loyalty missions are among the most crucial side-quests available in Mass Effect 2. Squadmate loyalty impacts several aspects of the game, including whether or not the particular character in question will survive to see the next game. The condition even survives into Mass Effect 3 where characters can once again face devastating consequences should they not trust Shepard.
Tali’Zorah’s mission is called “Treason” and has Shepard represent her in front of the flotilla’s government.
Mass Effect Legendary Edition: ‘Treason’ Loyalty Mission Guide
Commander Shepard will eventually be made aware that Tali wants to speak with them partway through Mass Effect 2. If visited, Tali will explain that she has been summoned to the fleet to stand trial for treason. She has been accused of putting the entire fleet in jeopardy and will be exiled if the charges are proven true. Tali needs Shepard’s help to clear her name.
There are spoilers beyond this point—so those who don’t want to risk being spoiled should click away now.
Upon first standing before the Admiralty Board, the specifics of the charges are laid out: Tali is being accused of treason due to a geth attack on one of the quarian’s ships. The board believes it’s her fault for sending geth pieces to the flotilla. However, Tali argues that she was only doing so under direct orders from her father—who she assumed had recused himself from the trial to avoid a conflict of interest. Additionally, everything she sent was safe and deactivated.
Speaking of which, where is her father, anyway? Oh, he’s on the ship that was taken over by the geth. How terrifying and convenient for the squad.
As her captain, Shepard is tasked with speaking in Tali’s defense. They will be able to cut a deal with the board to reclaim the ship and search it for evidence to figure out what actually happened. The board agrees with this and suspends the trial until Shepard and the squad have returned.
Shepard has the chance to speak with all members of the Admiralty Board, as well as the two quarians they had the chance to save—should they have survived. They’ll either provide necessary support during the trail should the squad need it or explain they’ve already given testimony on Tali’s behalf.
Upon boarding the ship, the overflow of geth is apparent. The squad will have to fight through several groups in order to reclaim the ship. Along the way, they’ll learn that Tali’s father has been reactivating and rebuilding geth in order to study them more closely. This is what led to the takeover—not Tali, herself. Unfortunately, the man ended up paying for this mistake with his life. The squad will eventually find his lifeless body and Shepard will be offered a paragon react to comfort Tali following the discovery.
Despite the clear evidence against her father, Tali will beg Shepard not to bring it up and not tarnish his name post mortem.
The squad will then return to the hearing just before the board moves to declare their ruling inabsentia. Shepard can choose how they’d like to proceed with the hearing. However, if they decide to use the evidence against Tali’s father, they risk obtaining Tali’s loyalty in the end. Both Paragon and Renegade defense options are available here to avoid Tali’s exile. Otherwise, the rest is in Shepard’s hands.