When those efforts proved in vain, Dumbledore had no choice but to take matters into his own hands. Filled with shame over his part in Ariana's death and held back by a secret blood oath, Dumbledore wished to avoid confronting his former friend and sent Newt Scamander and other allies to stop Grindelwald, instead.

He watched from afar as Grindelwald's power grew. Humbled by the death of his sister, Dumbledore decided he could not be trusted with power and choose to become a teacher at Hogwarts. Meanwhile, Dumbledore had seen the error of his ways with regards to his earlier ambitions. Grindelwald panicked and fled, and Dumbledore was left to pick up the pieces, along with a lifelong guilt over his role in the death of his sister. They started dueling, and Dumbledore was forced to take up arms as well. Grindelwald got into an argument with Albus' disapproving younger brother, Aberforth. The duo's dreams of ruling the world of Muggles and wizards alike as benevolent dictators were shattered, however, when Dumbledore discovered the extent of Grindelwald's cruelty. Together, Dumbledore and Grindelwald sought to confirm the existence and location of the Deathly Hallows.

Shortly after graduating from Hogwarts, Albus kindled a friendship (and romance) with the equally brilliant young wizard Gellert Grindelwald, recently expelled from his own school. His fame grew with each passing term, but he was frustrated in his ambitions by his responsibilities to his family, particularly after his younger sister, Ariana, accidentally killed their mother, leaving Albus in charge of the household.

Albus was a star student, and he carried out extensive research into theoretical areas of magic far beyond his years.

The harry potter book