Aberforth Dumbledore (c.1884–?) was the younger of the brothers by some three years, and the lesser skilled of the two. As such, he was usually left in the background while his brother basked in glory.
He became the favourite caretaker of Ariana Dumbledore because he was Ariana's favourite, and was known to have cared for her best as he could get her to eat whenever she would have normally refused for her mother.
Aberforth had gotten into an argument with his brother and his brother's friend, Grindelwald, which resulted in Ariana's tragic death. At Ariana's funeral, he publicly confronted his brother, breaking his nose.
Some time after, he became the owner of the Hog's Head inn. He was instrumental in the seventh book, greatly aiding Harry Potter in his mission to stop Voldemort. His pub became an evacuation route as well as a rendezvous point for the opposition to Voldemort.
Source: Wikipedia.
Note: This is a fictional character, belonging to J. K. Rowling. This is a journal for Role Playing and fanfiction writing purposes. No profit is made. I'm not Jim McManon either.