Alan Gaunt is the brother of Edward and Neil Gaunt. Alan and Neil were both very jealous of Edward's success and planned to killl him and steal his money. However, Layla found out about it and turned them into rottweilers. (Edward pleaded with her to spare their lives) Ever since, they have been the family's household pets and have been shown to be very loyal and intelligent. When the twins suggested changing their names to Winston and Elvis, Edward was furious due to his strong connection with his brothers, even after their betrayal.
As rottweilers, they have shown to be extremely loyal and in the first book described as intelligent dogs who knew the difference between television channels and could understand speech.