Aislinn had the power to change into a blue unicorn. She fell in love with Frodo, then followed Frodo and Sam to Mordor.
Aislinn was charged with "disrupting the canon by being a member of a nonexistent species, interfering with the characters of—mainly Frodo, and Sam as well; and being a Mary Sue."
The Sue, in unicorn form, was caught in a snare made of invisible yarn, and Jay (being a virgin and thus traditionally allowed to do this sort of thing) lured the unicorn into laying its head in her lap. This allowed Acacia to charge and shoot the unicorn.
Jay and Acacia sawed off the dead unicorn's horn (which came in handy later) and brought the rest to Luxury, who stuffed its head and turned its skin into a nice blue rug in exchange for an invisible scrunchie.