Zaeed Massani is a mercenary from the Mass Effect universe and one of the founders of the Blue Suns mercenary group. Though he is a recruitable party member in the second game via Downloadable Content he is also by far one of the most ruthless and amoral party members of all, as is especially evident during his Loyalty Mission.
Zaeed Massani co-founded the Blue Suns mercenary group alongside another man by the name of Vido Santiago. For a time, the partnership was successful, as Vido was the bookkeeper and Zaeed the field-leader. However, tensions developed between the two when Vido advocated hiring Batarians, who he viewed as cheaper labor. Zaeed however, saw the Batarians as terrorists and refused. This would be only one of many incidents where Zaeed's moral standards kept Vido from making money. Eventually Vido decided that Zaeed needed to go and betrayed him, seizing control of the Blue Suns after shooting Zaeed in the face. Attributing his stubbronness and desire to exact revenge as the reasons for his survival, Zaeed vowed vengeance and spent the next twenty years hunting Vido, trying to find him.
Eventually, he was recruited by Commander Shepard to take part in the fight against the Collectors. It was around then that Zaeed had finally tracked down his nemesis to the planet Zorya. Tricking Shepard into thinking that he wanted to liberate the Blue Sun's slave workers, Zaeed got Shepard to go with him to Zorya, at which point Zaeed made clear his vendetta, also explaining his history with Vido to a curious Shepard. Confronting Vido, Zaeed started a fire, knowing it would slow Vido down, but also knowing that it would endanger the innocent workers. What happens next depends on the player. A Paragon Shepard will be disgusted with Zaeed's callousness and obsession with revenge and will force Zaeed to help them save the trapped workers, which Zaeed begrudgingly agrees to, but in doing so Vido is able to escape. Zaeed is enraged, but Shepard points out that as they are now a team they must work together, and no one can put their own selfish agenda ahead of the greater good. Conceding that Shepard has a point, Zaeed agrees to put off his ongoing vendetta long enough to complete the mission.
Conversely, if the Renegade option is chosen, Zaeed gets his revenge on Vido, gleefully burning him alive, but also allowing innocent people to die as well. Yet a third option is if the Paragon resolution is chosen but then the player chooses a renegade option of leaving Zaeed to die, remarking that as Zaeed started the fire it is only fitting that he himself burn in it. This option is only available if the Collectors have been defeated and Zaeed is alive.
If he survives the battle against the Collectors, Zaeed returns in Mass Effect 3 for a side-quest that if completed successfully will allow Zaeed to become a War Asset. However, if Zaeed was not loyal in the previous game he will die during the side-quest. He can be contacted on Earth before the final battle and also appears in the Citadel DLC.