Sibling Arrivalries - S5.E4

Church finally discovers that Vic's voice mailbox is full. The Red reinforcement who emerged from the ship is revealed to be the Sister of Grif, who by Simmons' theory arrived using the ship's light drive, which caused her and the ship to move forward in time as it was traveling to Blood Gulch. Meanwhile, it is revealed that Donut fell into an underground cave (Waterworks in Halo 2) after the ship crashed on top of him.