Donny is an unorthodox, but extremely successful attorney. He first dated Roz Doyle (prior to the show), before he was hired, on her recommendation, as the divorce lawyer for Niles Crane. While working on Niles' case, he becomes acquainted with Daphne Moon, to whom he gets engaged. Donny isn't at first the expectation of Niles and Frasier, but his bold attitude changes their mind. His nickname in legal circles is 'the Piranha', although Roz deflates this by explaining that he has a 'night-grinding problem' with regard to his teeth. Donny successfully wins Niles a large divorce settlement without the need to go to court by unearthing the source of Maris' family fortune - not timber, as she has always claimed, but urinal cakes. After this, he begins seeing Daphne. He is eventually left at the altar by Daphne, in favor of Niles. He becomes sour after being abandoned, and files a lawsuit against both Daphne and Frasier, the latter of whom he holds responsible for advising Daphne to forsake him. He later drops both lawsuits. Donny eventually marries a woman he knew for only two weeks. In "The Ring Cycle" he meets Daphne and Niles when he is about to marry another woman. It then becomes clear that he is still not over Daphne leaving him. He received his law degree from the University of Las Vegas, a fact which provokes barely masked derision from Niles when he first learns it.