Brandywine is a female, purple-coloured dragon and somewhat inbetween Darm's pet and assistant.
She's living together with Darm in his hut amidst the Timbermist Woods. It's questionable and never answered how she is able to enter and leave the hut, what she is undoubtedly doing, according to the opening-scene of The Legend of Kyrandia: Book 2 - The Hand of Fate, where you can see her in the Royal Mystics' library or once again in the opening scene of The Legend of Kyrandia: Book Three - Malcolm's Revenge, where you can watch her flying upwards towards the player's monitor screen. (Curiously she's "attacking" the player by spitting some firing bursts before noticing that the player's no hostile intruder but a well-known visitor to Kyrandia. As it seems Brandywine is or became also some kind of a guardian to the magical world.)
As Darm's assistant she's mainly correcting her master's tangling gibberish, jogs his memories or helping out in general with useful information. Obviously (by her speaking tone or rolling her eyes) she's at least slightly annoyed by Darm's - probably age-related - confusion.
Brandywine and Darm behave like some old married couple teasing each other with provoking actions: When Darm lessons her that HE is the Master of Scrolls and Brandon came to him for his advice (because Brandywine intervened and told Brandon all the relevant information), Brandywine spits a flame towards Darm setting his magician's cusp cap on fire. Unimpressed but obviously provoked he drums his fingers on the desk and asks her if he's smelling again some cat-odour from her breath again. Brandywine "shrugs" more or less excusing and states back if it is her fault that she doesn't like knights. (Explanation: "All sweat and muscles ... and so hard to peel.")