Armida is a powerful sorceress, summoned by Mister Pullman as part of a plan to make Tom Taylor lose his virtue and thus leave him unable to use the holy grail. Using shape-shifting powers and slight mind control, Armida tricks Tom's friends into believing that he raped her. The ruse is mostly successful, however Armida's evil nature is revealed when she attempts to enter the chapel of the holy grail but is repelled by the chapel's barrier against evil.
Realizing that she can't enter the chapel to steal the treasure from Tom herself, Armida flees backwards through time in order to fashion herself a weapon to use. (The Unwritten: Apocalypse #7 - #8)
While looking over Tom's time/storyline, Armida discovers Daniel Armitage, an innocent young man tangentially related to Tom who honestly wants to help. She sends him an omen ensuring that he will know where to find Tom in Brisbane, Australia and thus be able to ensure the boys become friends. (The Unwritten #35.5)
Daniel does eventually meet with Tom and earns his trust and friendship, and Armida waits for the perfect moment to then pull Daniel out of Tom's story. While Tom is away in the underworld and all other characters are too wrapped up in their own plots to notice Daniel, Armida appears to him under the guise of a coyote in a dream and lures him off into another world, announcing that he's the man who killed Tom Taylor. (The Unwritten #44)
Armida then disguised herself as a mysterious veiled lady in an unending forest, and cryptically tasked Daniel with shooting her in the head. Any time Daniel refused, he would run in another direction and wind up back where he started from. Armida's hope was to drive Daniel mad enough to believe that killing someone innocent could honestly be the right option. After a year of this purgatory, Daniel finally shoots Armida, at which point she cast the illusion that she was now some kind of butterfly woman who was freed from her cocoon through the righteous act of being shot. (The Unwritten: Apocalypse #2 - #3)
With Daniel now mentally unbalanced but still believing at his core that he is a good person, Armida then leads him to believe that Tom too must be killed in order to grant him the kind of blessed rebirth that Daniel had just supposedly given her. Armida takes Daniel to the chapel of the holy grail where he stabs Tom Taylor in the back at Armida's behest. He hands Armida a trumpet that had materialized before Tom, at which point she burns him to death, having no more use for him. (The Unwritten: Apocalypse #8)
Realizing that the trumpet can only work within the fictional world of the "Tommy Taylor" novels, Pullman sends Armida into that story in order to pass the trumpet on to the story's villain, Count Ambrosio. Ambrosio gladly takes the trumpet, but burns Armida down her bones while doing so. (The Unwritten: Apocalypse #10)