Who is Miss Avocet from Miss Peregrine's Home for Peculiar Children and what is their importance?

Miss Avocet is another ymbryne, one who supervises a loop some distance from that supervised by Miss Peregrine. Miss Avocet evades kidnapping by one wight and makes a desperate effort to warn Miss Peregrine that the wights are on the move, but is later captured, along with Miss Peregrine, by the Golan wight. Miss Avocet is taken hostage by the wight/Nazis, leading Jacob and the other peculiars, along with Miss Peregrine, to take on the mission of rescuing her.