Old and geezerly, with a cain.
Grandfather was the leader of the Wardens of Cerberus during their golden age and for several years into the organization’s decline. His current whereabouts are unknown but his disappearance coincided with Scarlet’s release from Zanzar Tem’s circle and Sabrine’s reveal as a traitor.
Grandfather oversaw the induction of the new Spectre’s into the Wardens of Cerberus and assigned Malek to train them in secret.
From the few interactions he’s shared with the new Spectres it is clear that his influence on the wardens was one of benevolence.