Heretics (Faction)

Summary
Originally a Covenant artifact retrieval team attached to the Fleet of Particular Justice, the faction of Grunts and Elites now dubbed "Heretics" and led by Sesa 'Refumee were investigating a Gas Mine on Threshold when the UNSC Pillar of Autumn crashed on Installation 04. When the Master Chief destroyed the Halo, the Heretics were spared from death.

A few days later, the Monitor of Installation 04, 343 Guilty Spark, arrived at the gas mine. He promptly took command of the Sentinels running the facility, and began informing the artifact retrieval team of the true purpose of the Halos.

Disillusioned with the lies of the Prophets and their Great Journey, Sesa 'Refumee began open rebellion. He sent holographic recordings to other Elites hoping to open their eyes as well. In the meantime, he strenghened the defenses of the Gas Mine, fortifying it with Plasma Cannons and a large compliment of Banshee fightercraft. He also had at least one Seraph fighter.

It is unclear how many more Elites 'Refumee was able to sway to his cause, but his significant military force and strong words attracted the attention of the High Prophets, who decided to put the "Heretics" down with two other former commanders of the Fleet of Particular Justice; the disgraced Arbiter and SpecOps Commander Rtas 'Vadumee.

In the meantime, the Heretics on the Gas Mine discovered that the facility was refit into a Flood Research Facility when they accidentally released the Flood upon themselves. They began a battle throughout the entire mine to contain and destroy the Flood.

The Arbiter and Rtas 'Vadumee arrived at the facility with three Phantoms full of Special Ops Elites and Special Ops Grunts and, despite heavy resistance from the Heretics and the Flood, were able to kill Sesa 'Refumee and destroy the gas mine completely.

This was a crippling blow to the Heretics as a faction. It is possible that they were able to recover though, as Halo 2 Multiplayer maps suggest the Heretics operated a base on Basis as well.

Appearance
Having abandoned the ideals of the Covenant entirely, Sesa 'Refumee decided to carry a new banner for his troops; the beige and gold colors of the Sangheili homeworld. The Elites and Grunts donned new armor of these colors as well as outfittings to help them survive in the Hydrogen atmosphere of the Gas Mine.

The Heretics also changed the appearance of their vehicles; the Heretic Banshees and Seraph had much of their external plating ripped off, revealing the Forerunner based workings within. They were also repainted to bear the colors of the Heretics and the Sangheili world.

Heretic Grunts
Heretic Grunts wield Needlers, Fuel Rod Cannons, and they can also man Plasma Cannons. They have never been seen using Plasma Pistols, the weapon more commonly used by their regular, non-Heretic counterparts, although a fair amount of Plasma Pistols are scattered throughout their base of operations. They are also not as suicidally stupid as their Covenant counterparts, and they never panic or run away. They are also noticably tougher and harder to melee due to their reduced armoured re-breathers.

Heretic Elites
Heretic Elites seem to use either Carbines or Sentinel Beams. This probably means they use reloadable weapons instead of making multiple weapons. Apart from the Heretic Leader himself, they never use the Plasma Rifles wielded more often by their regular counterparts, although if you board a Banshee piloted by one, the pilot will be wielding one. It may be possible that there is also a ranking scheme for the Heretics due to the fact that some carry Plasma Swords, although this could be dismissed as there is no difference in armour colouring, shield strength, and the fact they they have to retro-fitted Covenant technology. This could mean that they use what they steal when they defect, or they utilize what they find and scavenge.