Your Makuta outwardly always acted like a kind, understanding and nice fellow, but behind this mask actually manipulated and exploited everyone to benefit the Brotherhood and himself
Your Makuta sided with Teridax at the Convocation
Your Makuta was assigned to the island of Kurai. On Kurai, he for a long time exploited the local resources by manipulating the natives, then, after eventually they started seeing through his true intents, your Makuta called the Visorak horde to clean up after him and left the island.
This process of exploiting the region nearly to exhaustion, then leaving, he repeated several times in different regions
Some time after the Great Cataclysm, rumors of riches to be found there led your Makuta south, beyond the border of what was considered the known universe. It is uncertain what exactly happened to him there - maybe he made a mistake or maybe the inhabitants of these regions couldn’t be manipulated as easily. Fact is, he never returned, and Teridax later found out that your Makuta’s Protosteel armor had been converted into tools by the natives of the south.
Rules and list in post 1 All Makuta are currently assigned
he fought in the battle against the League of Six Kingdoms
he was assigned to the island of Tevan
at the Convocation he was faced with the dilemma of staying loyal to Miserix and Mata Nui, or staying loyal to the Brotherhood of Makuta and honouring the opinion of most of his brethren. Since he could see that Miserix was losing the vote and could guess at what awaited those Teridax saw as his enemies, he eventually joined Teridax’s side.
On Tevan Barrion started influencing the culture of the inhabitants, promoting honor and loyalty and more and more becoming a kind of judge to the locals
After the Makuta had banished their inner light, Barrion’s understanding of honour and loyalty eventually became twisted, with him eventually openly making a grab for power and having any who protested brutally executed as traitors, often even performing the executions himself for the enjoyment. The executions of many clan leaders led to political instability, however, and soon wars broke out on Tevan, resulting in Barrion leaving the island to look for a people that was worthy of being ruled by him.
not finding anything to his satisfaction, Barrion eventually called for the Visorak Horde to pacify Tevan. Following that he established an unsteady rule which constantly had to deal with local rebellions which became even worse after the Great Cataclysm. While he successfully managed to hold the island against a Dark Hunter army later, it weakened his troops too much to be able to resist the next revolt. Still bound by honor and loyalty to the Brotherhood, Barrion refused to give up, however, even after his forces had been wiped out. He died on the battlefield.
I guess death in battle isn’t terribly original either, but I feel like it’s at least something that’s readily acceptable.
(By the way the stuff about what’s going on on Tevan has a basis in canon/RSG lore)
Rules and list in post 1 All Makuta are currently assigned