When the Atlantis expedition sends a M.A.L.P. through the Stargate to Asuras, Niam communicates with them through it, telling the expedition that if they come in peace, they are most welcome. When the First Atlantis Reconnaissance Team and Doctor Elizabeth Weir come to Asuras, Niam greets them and takes them to meet with the High Council, led by Oberoth. Along the way, Niam tells the team some facts about the Asuran city, the number of Asurans and how many ZPMs they have. Niam's interest is drawn when the team mentions the Ancients achieving Ascension due to his own desire to do so.
After the meeting with the High Council, Niam escorts the team to living quarters and indicates to them his own dissension with Oberoth's beliefs. He is later surprised when Oberoth betrays the team and in Lt. Colonel John Sheppard's fantasy, is used as a hostage to help them escape. After Oberoth takes the Asuran city-ship to destroy Atlantis, Niam convinces his leader to spare the team and explains the situation to them. Niam shows Weir through a mental link the true history of the Asurans and he and his faction offer a deal wherein Doctor Rodney McKay removes the aggression command from their base code and they convince Oberoth to stop the attack on Atlantis. McKay is able to remove the directive from Niam who will spread it to the other Asurans in their periodic updates, but also comes up with a way to freeze all of the Asurans. Niam alone is unaffected and while confused, realizes that there's no guarantee he can convince Oberoth to desist and aids McKay in setting up a ZPM overload to destroy the city. As the Asurans start to unfreeze, the team and Niam escape in a Puddle Jumper as the city explodes behind them.
On the Puddle Jumper, Weir reassures Niam that he did the right thing, but Niam warns everybody that the Replicators on his homeworld know what he's done and are resetting him. With his aggression restored, Niam immediately starts strangling Weir before Sheppard knocks him into the back of the Jumper and blows Niam out into space (SGA: "Progeny")
Shortly after the destruction of the Asuran city-ship, its discovered that Niam infected Weir with some nanites when he strangled her in the Puddle Jumper. As Weir tries to make her way through the Stargate back to Atlantis in her dream world, the nanites infecting Weir take on the form of Niam to taunt her that they made Sheppard disappear and she can't defeat them. Weir walks through the image of Niam, causing it to collapse into Replicator blocks and goes through the Stargate, freeing herself from the nanites Niam infected her with. (SGA: "The Real World")
When the Asurans take control of Atlantis, a plan is devised where the First Atlantis Reconnaissance Team, Doctor Carson Beckett and Doctor Weir retrieve Niam from space and use him to upload another freezing program to the Asurans, allowing the team to kill them all at once with Anti-Replicator guns. While the team successfully retrieves Niam, who has been rendered inactive by being left in space for months, Talus learns of the plan from probing Richard Woolsey's mind. As a result, the Asurans reactivate Niam before McKay can upload the program. As Niam charges McKay, McKay shoots him with an ARG, causing Niam to collapse into nanite dust and killing Niam, foiling the team's plan to defeat the Asurans. (SGA: "The Return, Part 2")
After Weir is mortally injured following the Asuran Stargate satellite attack on Atlantis, Doctor Jennifer Keller reminds Doctor Rodney McKay of the nanites Niam infected her with and suggests reactivating them to heal Weir. McKay eventually reprograms Niam's nanites to be non-harmful to Weir and to heal her, but they leave her part-Replicator as a result. (SGA: "Adrift")
In order to buy Sheppard, Ronon and McKay time to escape, Weir uses her new abilities to link with Oberoth and take control of the Replicator collective. Oberoth is shocked by her ability to do this and Weir explains how Niam had infected her with nanites which they had then reprogramed to suit their needs. After being informed of this fact by Weir, Oberoth notes he can sense the nanites now, having not previously been aware of Niam's actions after he was reset. (SGA: "Lifeline")
- Niam is the first known being killed by Doctor Rodney McKay. Unlike the other members of Sheppard's team, McKay is not known to have killed anyone before he destroyed Niam with an ARG.