Angels - M

Metatron = A great and powerful Angel, Metatron is often referred to as God's Scribe. He is said to have been placed by God at the heart of the Infinite Library, where he acts as the Master Librarian. Obviously Angels who follow in his path will come to resemble the Order of Librarians. 
St. Michael the Archangel = A great and renowned general in Heaven's armies, Michael is credited with being the warrior who personally drove Lucifer into Hell following the First War. Michael is commander of the Warrior Angels and he often personally delegates over the Legions. Michael is the patron of the Order of Destroyers, and Archangels who follow him especially will develop some of the Destroyer powers. For more info see Michael.
"Monkeys" = Derogatory term for humans, normally only ever used by the Rogue Angels.
Music = Celestials are avid lovers of music (in case the Acoustic Angels weren't proof enough).