Here's a closer look at the Spartan fireteam taking up residence in Agent Locke's surprisingly ornate chest cavity - led by none other than poster-mate, Master Chief. The official Xbox news story says these teams "play a crucial role in the showdown between the Master Chief and Spartan Locke".
And here's Locke's fireteam, an altogether sleeker-looking bunch. There's no word on whether these particular groups will be campaign characters, a la Halo: Reach, but there's definitely an air of inter-Spartan conflict going on.
Completing what seems to be the game's hate triangle is the colossal desert-robot-thing from the original Halo 5 reveal trailer. It bears the anti-gravity hallmarks of Forerunner technology, but it's flanked by Covenant Banshees.