Cortana (Halo 5)
Gaming is all about bonds, and the Halo games are defined by the relationship between Master Chief and Cortana. Over the past decade and a half, players have grown attached to their AI partner, and when she sacrificed herself to stop the Didact in Halo 4, fans were wondering if she actually was gone for good. Sure enough, she’s back in Halo 5, but not in the way people were hoping for.
All AI suffer from the seven stages of Rampancy, and when you first hear her voice again, she says that the Forerunner world Genesis has cured her. Which would sound like a good sell, if it weren’t for the fact that she’s activating powerful Guardians that wreck the planets they’re buried under. Even before you actually meet her in her new and improved form in the penultimate mission of the game, it’s clear that she’s more dangerous than she let on. Her fall from hero to villain is compelling, and it’ll be interesting to see how this plays out in future games.