Double Diamond is a white Stallion, who was one of the many ponies Starlight Glimmer lied to in the season 5 premiere. Double Diamond helped Starlight, and acts as an assistant to her- From spying on the main six, to bringing them to her on their arrival, and to even bringing the cutie marks from the vault to Starlihgt when she requested them, he seems to have a stronger relationship with her than the rest of the ponies of the town. However, when finding out she'd lied to them, he's quick to turn against her.