Gianna Parasini
Role:
In the side quest “Investigate: ExoGeni” Gianna Parasini discovers that ExoGeni is one of the front corporations for Cerberus, studying Reaper technology gathered from Sovereign , and sending their findings back to TIM. At the conclusion of her investigation, Gianna (provided she survives the mission) is able to tie the corporation to Cerberus, causing ExoGeni to shut down indefinitely. This financially cripples Cerberus, which is already financially devastated from expenses of the Suicide Mission (ME2), hiring hundreds of mercenaries, and having Liara use her Shadow Broker resources to shut down Cord-Hislop Aerospace Corporation (Cerberus's biggest Corporate front). Gianna can also be hired by Liara (the Shadow Broker) to monitor the possibility of Reaper spies on the Citadel.
Mission – Investigate: ExoGeni
Liara discovers that, while most corporations on Illium are struggling to make money, there is one corporation that has not been effected by the Reaper war: ExoGeni. Normally she wouldn't pay something like this much mind, but one of Liara's field agents heard a rumor that ExoGeni was experimenting with the most advanced dark energy technology ever created since before the Reaper invasion– and that they bought technology from salvage dealers who had all previously helped clean up the Citadel three years ago. Shepard connects the dots, and realizes that ExoGeni must have bought pieces of Sovereign's remains. He decides to investigate these claims personally, by breaking into the Illium tower where ExoGeni is currently housed.
Shepard finds Gianna outside the entrance of ExoGeni, where she is arguing with the guard. She has a police approved search warrant, but is being denied entrance because, according to the guard, there is no admittance after closing hours (it is a late evening). Gianna exclaims that she arrived late so she could check out the items ExoGeni has been importing/exporting from the tower after-hours, but the guard, obviously just doing her job, tells Gianna that she cannot be admitted. Shepard approaches, and the two women catch sight of him. Depending on whether Shepard helped or hindered Gianna in the past games, she will either be happy or annoyed to see him. Gianna asks if Shepard could possibly authorize Spectre clearance for her to enter the building.
If Shepard is a Spectre, he can authorize Gianna and his admittance. He can also authorize only his own admittance (if he wants to be rude to Gianna), leaving her outside to continue arguing with the guard. Shepard will either bribe he guard, or threaten/charm the guard into not telling ExoGeni's employees that he is present. Once inside the main lobby, Shepard and company take the elevator down several levels to the tower's stocking station.
If Shepard is not a Spectre, they cannot enter legally the facility. Luckily EDI manages to hack a platform (for washing windows) on the side of the balcony, out of sight from the guard. Shepard and Gianna can sneak onto the platform, and be lowered down the building into the unlit depths of the Illium skyline. The platform takes them to an open window in the tower's stocking station.
After searching the ExoGeni loading station, Gianna scans a shipping and inventory manifest. Records show that ExoGeni shipped several crate containing Reaper technology to the planet Feros. Shepard and Gianna prepare to leave the loading station, but at that moment, Cerberus soldiers enter the room to commence security sweeps.
Shepard can direct Gianna and his squad-mates from cover to cover, avoiding the guards. The company make their way to the window where the lift platform is, and take it back up the side of the building. Alternatively, Shepard and company can sneak their way onto an elevator, and leave the ExoGeni headquarters right through the front door – humiliating the guard.
Shepard can attack the guards. If he does this, Gianna will have limited health bar. Once the bar is too low, Gianna will be mortally wounded, and will die. Shepard and company must take the elevator back up the building.
Gianna stays at a bar on Nos Astra, gloating over the information she recovered. She explains, however, that without physical evidence of Reaper technology, ExoGeni could escape potential conviction. Parasini asks Shepard to go to Feros, and collect as much information on the corporation's shipped items as is possible.
Shepard can agree to this, making the mission “Investigate: Reaper Technology” on Feros available. Shepard can also decide he doesn't have time to investigate, much to Parasini's annoyance.
If Shepard was aligned with Cerberus, he can keep the data for himself. If Shepard gives Cronos station to Miranda/himself, the information on Reaper studies will make his organization worth more EMS.
If Shepard completes the side quest on Feros, and brings some of the data back to Gianna, she will be able to successfully charge the entire ExoGeni Corporation with treason, assisting terrorism, illegal experiments, and multiple accounts of murder – resulting in her becoming rich. Despite her new found wealth, she prefers to live with simple comforts, and moves to a small apartment on the Citadel. Shepard can talk to Liara, and convince her to offer Gianna employment as a Broker agent (though Gianna will never know about Liara's alter-ego, or visit the Shadow Base).
Romance:
Male Shepard can romance Gianna, assuming he completed her sidequest, and the sidequest on Feros, and returned her the data. Gianna's romance consists of having a date at club Purgatory on the Citadel, visiting the Victim Memorial wall in the presidium, letting Gianna tour the Normandy, walking Shepard to and from the Hegemony Trials, visiting her penthouse, etc.
Ironing out variables:
If Gianna died in ME1, she does not appear in ME3. Shepard infiltrates ExoGeni's stocking station without her. Liara can use the information Shepard discovers at Illium and Feros to either extort money from ExoGeni, or shut the corporation down.
If Shepard either betrayed or did not complete the previous games' missions with Parasini, he cannot romance her.