Rupert is a good girl. Yes she is.
Rupert is a young drachen given to the party by the spirit of Eisen currently sharing brainspace with Hans von Wische. It’s complicated. She is female, but Ailsa named her, and are you going to tell Ailsa that she can’t call a female drachen Rupert? Along with the drachen itself, Hans/Eisen added an enchanted collar to disguise her as a hunting dog.