Cortana bickering with Wheatley: think about it. The two are strong personalities in their own rights, but put together they make for some hilarious banter.
I would never have imagined Wheatley's deadpan humor to work so well under the seriousness of Halo's plotline, but apparently Toadking07 did and I'm all the happier for it.
Wheatley is 343 Guilty Spark - Halo Combat Evolved Anniversary Edition [YouTube]