See post #3400877.
She is extremely loyal and doting to the Commander and will address them as "Honourable Master", but is somewhat clumsy and accident-prone. Her primary role, however, is as a bodyguard and she excels at combat as a result; she just does other duties out of her devotion to the Commander. Sirius also displays a barely-hidden lewd side, often offering to service the Commander if the "Special Touch" is used before correcting herself. Because of her physical traits and personality, she rivals Belfast in popularity among the Royal Maids.