Trion

Trion was once a planet under the complete control of the , used for research on a large selection on biological species that the Forerunners monitored and cataloged previous to the. The control of Trion would later be taken over by the rate when the Forerunners war with the Flood were at its highest. The planet had two rings constructed around it to serve as residential areas for soldiers and as a line of defense to both defend the planet from outside treats and to glass the surface should a  infestation grow out of control. Trion would, during the war with the Flood, experiment with the Flood parasite on the many species down on the planets surface in the attempt to find a cure or an effective way to combat the parasite. The planet would eventually fall to the Floods unstoppable advances across the galaxy and then many thousands of years later, be rediscovered and colonized by the Ember Coalition that then would claim the planet as their capital as they reformed into the Ember Federation.

Pre-Forerunner-Flood War
Before the war with the Flood the planet was considered of little importance due to its remote location from the Human-Forerunner War and could be classified as a backwater world by Forerunner standards. The planets population consisted mostly of low ranking Lifeworkers that monitored other species evolution as well as cataloging new ones whenever they showed up. Small bits of research within the biological and genetic fields were done but nothing of major importance.

During the war
The Lifeworkers continued their work in complete ignorance during the early stages of the war with the Flood parasite but in the end lost contact with an increasing amount of Lifeworker teams that reported to Trion. This Got the Builders to move in and take control of the planet. Builder Security forces occupied the planet and turned it into a staging point and their base of operations for their forces to battle the Flood without the Lifeworkers knowing anything. The Lifeworkers were eventually forced to help Builder scientists experiment with the Flood parasite. To make sure that no Flood related threats entered or left the planets atmosphere, the Builders constructed two massive rings around the planet itself. These rings would function as the Builders exclusive residing areas and to contribute to the planets defenses. The planet would be assaulted by waves of of infected fleets controlled by the its ally, the rampant,. The Builder Security forces were successful in repelling the constant assaults but slowly weakening from the many battles. The Planet finally fell to the Flood when an outbreak down on the planets surface grew out of control during a Flood naval assault. The Need to split their force in two to combat the fronts proved to be the Forerunners downfall as they were surrounded from the outside and from constant streams of transport coming up from the planet.

Rediscovery and colonization
Trion was rediscovered by the Ember Coalition in the year by the use of the Guardian of Normas slipspace portal. Detecting Flood infection on the two rings and down planet side the Coalition send in boarding parties to take control of the rings command centers. The battles across the large rings were blood but with the help of Aggressor Sentinels and the Coalitions own attack bots they were able to secure the rings in orbit around Trion and subdue the Flood infection after three months of battle. Having secured the rings, the Coalition quickly restarted the the rings many Sentinel manufacturing facilities to boost their forces for the invasion of Trion. The Coalition waited 20 days before sending down their Sentinel armies to deal with the remaining Flood infection.