One of Kappus' tasks was opening locked doors. He was ordered by Captain Jacob Keyes to open the door that just so happened to be the only thing holding back the Flood. Unwillingly and unknowingly, Kappus unleashed the Flood on Installation 04, dooming him and the rest of his squad, save for Sergeant Johnson and Bisenti . When Riley was attacked by an Infection Form, Kappus successfully managed to pull it off, but others soon found Riley. Kappus was one of the first to be transformed into a human Combat Form.
- In Halo: Combat Evolved, his role in the game is often mistaken for that of Mendoza's because their character models are the same in-game. In Halo: Combat Evolved Anniversary, different models are used for Kappus and Mendoza.