Aberforth’s Relation To Albus Was Hinted All Along
When Harry enters Hog’s Head for the first time, he notices that the bartender looks familiar. In the sixth book, we come to know that Voldemort came to Dumbledore looking for a job at the school and Dumbledore tells him that he knows that there are many Death Eaters waiting for Voldemort in Hogsmeade.
Voldemort remarks that he is omniscient as ever but Dumbledore replies, “Oh no, merely friendly with the local barmen.”