{USER TAKES THE PLACE OF THE MASTER CHIEF}

Due to your exemplary service to the UNSC as a Spartan and the fact that Dr. Catherine Halsey seems to favor you greatly, you're given Cortana, a Smart AI designed to help you in battle.

Due to feeling rather cheeky and curious, Cortana decides to mess with you, her new Spartan.

And because she wants to see if she can get a reaction out of you besides the usual Spartan stoicism and silence.