She is a major character in 'Mariel of Redwall', and even more so in its successor, 'The Bellmaker'. In both books, she is renowned especially for her skill with a sling, bow, javelin etc., earning her the nickname 'Hawkeye', and for her annoying tendency to laugh tremendously at the most inappropriate moments.
In 'Mariel of Redwall', Rosie is a good friend and comrade of Colonel Clary and Brigadier Thyme, also of the Long Patrol. Sadly, both hares are killed while fighting against overwhelming odds. Rosie, who takes part in the same battle herself, very nearly dies of her many grievous injuries, but does not, owing to the fact that Flagg the otter, from Redwall, and Mother Mellus, badger mother of Redwall, find her while hunting down the searats responsible for the deaths of the hares.
Rosemary's ardent admirer, Tarquin L. Woodsorrel, another anthropomorphic hare, chases after her in 'Mariel of Redwall'. He remains firmly convinced that he is the apple of her eye, and he composes atrocious love ballads in her name. At the end of the book, we learn that he has married Hon Rosie, and that they have had several baby hares (leverets).
In 'The Bellmaker', Rosie is chosen by the spirit of Martin the Warrior to leave her husband at the Abbey and to embark upon a quest to find Mariel 'Gullwhacker' and her friend, Dandin the Sword Carrier, along with Mariel's father, (Joseph the Bellmaker), Rufe Brush (the Abbey bell-ringer), Durry Quill (the Abbey cellarhog) and Foremole (the head of moles in Redwall Abbey). The five set out to find the two adventurers. They meet some good friends on the way, and in the battle that takes place at the end of the book between the woodlanders of Mossflower Woods and the tyrant fox, 'The Urgan Nagru', over the land called 'Southsward', these friends help them to win the war. Four of the travellers, including The Honourable Rosemary, return safely to the Abbey with Mariel and Dandin, but Joseph chooses to stay with the inhabitants of Southsward to help them rebuild their homes. Hon Rosie settles back into the quiet Abbey life with her husband, Tarquin, and their leverets.