I made this topic so we could discuss how the Brotherhood of Makuta could be represented in the story as a faction and it's characters. As of now we know that the Brotherhood's goal is to revive Makuta, the Rahkshi are Matoran/Rahi hybrids and that they'll steal and shatter the Mask of time.
Firstly, I think the Brotherhood should start as an apparently benevolent but shady cult to Makuta, possibly with temples/buildings in the villages, and that they would try and gather more Matoran to their side, maybe with promises of evolving oneself to something better or surpassing their weaknesses, wich would eventually lead to certain member of the Brotherhood becoming the Rahkshi. I think it would also be interesting if they had this kind of reverence to the Rahi and their attributes, like strength, endurance, speed, etc.
Since all the Matoran now have some kind of manifestation of their elemental powers, maybe those Matoran that joined the Brotherhood could have, apart from their own element's power, some kind of Shadow powers or amplified/corrupted elemental powers.
In another topic, @DarkHenrik suggested that Ahkmou could be stealing important objects from the turaga and giving them to the Brotherhood. Maybe we could have it so that one of the things Ahkmou stole was some kind of book/scroll that mentions the Mask of Time and it's powers, leading to the Brotherhood looking for it and subsequently shattering it.
Anyway, these are just some ideas I had recently, If you guys have any ideas or suggestions you would like to share about the Brotherhood of Makuta, please do!