Jiralhanae Bodyguard

The Brute Bodyguard is a Brute (Jiralhanae) specialty rank. They are responsible for the protection of their packs Chieftain. They are also responsible for the enforcement of tribal law. Whenever there is a Chieftain nearby, you will encounter Brute Bodyguards which look very similar to Captains. Bodyguard Brutes are also seen to be protecting Truth on the level The Covenant. They are likely the replacement for the Honor Guard being that Tartarus also had Honor Guard protection. Brute bodyguards seem to favor Covenant weapons such as the Plasma Rifle and Carbine rather than their own native tech. They come in two variants: A more common, silvery-blue (with red underarmor) variant, and a less common, silver armored (with red underarmor) variant. Whether these variants signify differences in behavior or strength is unknown as of yet.They are first seen in Sierra 117.

Differences with the Brute Captain
The Brute Captains and the common Brute Bodyguard look the same (especially in dim light), but there are in fact slight differences in their Power Armor color. The Brute Captain Regulars have a violet tinge to the armor, but the Bodyguards have a more indigo color and their underwear is red. However in the heat of combat it is extremely difficult to differentiate between the two ranks. They cover for the brute honor guards in Halo 2.