Previous installments in the series (though not all) featured a special Easter egg encounter with a Special Dialog Grunt. Does Halo 4 feature such an encounter? If so, what are the requirements I must complete in order to see it?
No, there is no Special Dialog Grunt in Halo 4. Halo 1, 2, and 3 all had special dialog grunts, but no game since then has. This may likely be an easter egg that was left behind when the original trilogy ended. But, there are other easter eggs in Halo 4 to find.