The Angry Librarian is a seething mass of sheer fury. He visably shakes with rage just looking at him. When you address him he will respond in a calm, quiet, polite voice with a large clenched grin. They and they alone know the true injustice of the galaxy. They are denied all comforting thoughts that keep most men sane, but they endure because fuck if they're gonna let a goddamn pansy thing like absolute futility stop them. It just makes them angrier.
The Angry Marines keep their Librarians mostly in reserve. This isnt because they are weak, rather the opposite. The Angry Marines don't like how the Librarians get all the fucking kills. The fact that they don't see much combat just pisses off the Librarians all the more.