"No more Prophets! No more Lies! We are the Banished! We will not be stopped!" -Unknown Banished Warlord
Combine Caesars Legion, the Covenant, and monke, and you have the Banished. Masters of Gorilla Warfare, the Banished are basically the Orkz if they had 2 functioning braincells, but still didnt know how to use them.
One of the few universally praised editions to the Halo Universe that 343 (competitive) Industries has made to the Halo Universe. A Brute-lead Covenant rebel group started by Atriox, a Brute Cheiftan who was done with the Covenants shit, and not being respected as the epic monke he is. Slavery and unwilling members dont exist in the Banished, as Atriox only lets people who want to join the Banished actualy join them, as it was being forced into wars he did not care about that caused him to rebel from the Covenant. The Banished work as Mercenaries, and actually get payed for killing people, instead of just being told to believe in some "great journey" and that being their pay.
Atriox gladly works alongside a virgin Elite Shipmaster, because Atriox considers the Brute VS Elite Race-War a pointless waste of time, BUT, he is still totally ok with wiping out peaceful Human scientists on the Ark, because even in a pragmatic Mercenary militia that managed to survive the Covenant, the Xeno anti-Human hate-boner still reigns supreme.
The Banished were able to effortlessly survive the Covenant, a vast, multi-species, advanced version of the Imperium of Man, but when they try to take over the Ark and use it as a superweapon to ransom the Galaxy into their control, a single Human Warship known as the "UNSC Spirit of Fire" that has been drifting in space for 23 years AND has half of its soldiers killed by Flood and Covvies back in the day gives the Banished a run for their money, and they are able to curbstomp them to the point that the Humans managed to create a new HALO and intend to summon UNSC reinforcements to it. (Assuming Cortana doesnt fuck up that plan, like everything else)
Meanwhile back on the Ark, 2 Brute battle-brothers named Pavium and Voradus were wreckless enough to release the flood from the contained wreckage of High-Charity, the once flood-infested capital ship of the Covenant. (Master Chief blew that thing up, killing most of the flood there, but whatever) So not only is the Banished struggling against a UNSC ship they probably could have negotiated with if they resisted their Human hate-boner, they now have to deal with the Flood on the Ark.
Much later, the Banished somehow managed to take out many other UNSC ships and made their way to Zeta Halo, also known as Halo Installation 07. A Banished Brute soldier known as "Craig" was also killed by Master Chief there, but trust me, he wanted a way out.
(editional story info will be written here once Halo Infinite is released)
As a mercenary organization, the Banished are essentially a military hierarchy led by Atriox. Their prevailing philosophy is one of ruthless pragmatism, with their operations focusing solely on accruing useful resources for their war machine. They basically are trying to gain control of the Galaxy with force, force, occasional subtlety, and force. During the Covenant's reign, the Banished conveiniantly stayed quiet, so that way, 343 could explain how they just started appearing out of nowhere. Killing Covenant was never Atriox's ultimate target, instead only being leveraged as a source of supplies. It is possible that Atriox was planning to stabilize the Brutes on their homeworld Doisac under his leadership, however it is suspected that Atriox's long-term goals were even more ambitious.
The Banished basically took what the Covenant left behind, bolted some ugly metal plates over it, painted it red, and point them in the direction of their enemies.
Societal conditions within the Banished reflect their harsh values, and most of the organization's members are mercenaries and killers. Due to the Brutes being screwed over by religion in the Covenant, the Banished are pretty much athiest, and their only desire is for battle and power. However, some individuals (namely Decimus) secretly harbor a reverence for the Forerunners.
Atriox claims he has not animosity towards Humanity, yet he still wiped out a peaceful colony of Human researchers on the Ark, that he probably could have easily incorporated if he rained in his soldiers. Atriox admitted respect for his enemies tenacity and the fact that they were both survivors to the point that he offered the humans a chance to leave and in return, they would not be hunted down. However, Captain James Cutter refused the offer, because he is a badass.
The Banished have potential to become something truly memorable, but Halo Infinite will truly prove if they have it in them or not. Regardless, they are infinitely better than Cortanas Skynet Uprising.