He was a Death Eater but ultimately turned against Voldemort and helped Harry Potter.
Here's what happened:
* He was ordered to kill Dumbledore, but failed to do so.
* He was forced to continue serving Voldemort, but secretly helped Harry and his friends in subtle ways.
* During the Battle of Hogwarts, he disarmed a Death Eater, essentially saving his own life.
* After the war, he left the Death Eater organization and rejoined his family.
While he never became a close friend of Harry, he did choose to help Harry and ultimately played a role in Voldemort's defeat.