Master Chief (Halo)
MCPON John-117, or "Master Chief", is a fictional character and the protagonist of the "Halo" fictional universe created by Bungie. Master Chief is a playable character in the series of science fiction first-person shooter video games "", "Halo 2", "Halo 3", "Halo 4", and "". Outside video games, the character appears in books and graphic novels—"", "", "", and ""—and has cameos in other "Halo" media, including "", "", "The Halo Graphic Novel", "Halo Legends" and "".
Flood (Halo)
The Flood reappear in the "Halo 3" mission "Floodgate", on board a damaged ship that escapes the quarantine around Delta Halo. While the infestation of Earth is prevented, Master Chief and Arbiter form a tenuous alliance with the Flood to stop the activation of all the Halo rings at the Forerunner installation known as the Ark. Once the threat is stopped, the Gravemind turns on them. The Master Chief fights his way to the center of "High Charity", freeing Cortana and destroying the city, but Gravemind attempts to rebuild itself on a Halo under construction at the Ark. Realizing that activating the ring will destroy only the local Flood infestation due to the Ark's location outside of the Milky Way, the Master Chief, Arbiter, and Cortana proceed to Halo's control room, activate the ring, and escape. The Gravemind warns them that his defeat will only delay the Flood, not stop it.