In the Manga
Annette is an information broker and former sweeper who seems to have some old ties with Sven. She operates the Cait-Sith Cafe, an occasional haunt of Train and his companions. The name of her cafe, Cait Sith is a mythological reference. She is beaten up by Durham when he comes looking for Train for a duel and doesn't find him around.
In the Anime
Pretty much the same, except Durham in the anime does not meet her.