He can be seen as one of the game's antagonists and although he does not appear physically in the game, he speaks to Talion at various points throughout the story. Celebrimbor seems to know much about Curunir, despite the fact that the Istari arrived an entire age after the Wraith's death. Celebrimbor is somehow aware that the Morgai Flies are Saruman's minions, and that he is fighting Sauron to become the 'Lord of the Ring' of which there can ever only be one.
Fearing the threat of Sauron, Queen Marwen went into the Grey Mountains, where there she presumably met Saruman. When she returned to Núrn, she carried with her an elixir and through it falls into the will of Saruman. Her possession causes her to wither and make her seem older than she looks.
In order to obtain the elder elf's hidden knowledge of ring making, and possibly make a new ruling ring or learn the whereabouts of the original, Saruman reveals himself and attempts to absorb Celebrimbor into Marwen's magical staff. Talion is stunned while Celebrimbor is ripped from his body, leading Marwen's daughter, Lithariel, to break the staff, freeing both Celebrimbor and Marwen from Saruman's control. As soon as the staff is broken, color returns to Marwen's hair and face, and she grows visibly younger.
The White Wizard
I must see the Head of my Order. He is both wise and powerful. Trust me, Frodo. He'll know what to do.
One of the five wizards sent to Middle-earth to challenge Sauron, Saruman desires the power of the One Ring for himself, though he is not yet under Sauron's control. He spies upon Mordor from his tower in Isengard and is keen for any information about affairs there.
After Sauron's defeat and Isildur's death, Saruman's forces searched in vain for both Isildur's body and the One Ring that he carried. Though nominally a member of the White Council along with Gandalf, Saruman has decided to study the arts of the enemy for himself, and he hopes that Sauron's return will result in the re-emergence of the One Ring -- which Saruman can claim for himself. He's aware of Celebrimbor and the New Ring as well, hoping that a struggle between Celebrimbor and Sauron will at the very least weaken both parties.
Behind the scenes
Marwen's ailment mirrors that of Théoden's years later.