The gods of Sirran are not traditional gods, but rather the spirits of the first beings to live on Sirran. They are made powerful by the fact that all the spirits of the beings who die on earth join the gods upon dying. Like attracts like, and gods grow or wane in power as more souls of their alignment join them or are reincarnated. The gods themselves cannot ever be incarnated by normal means.
The souls of those who join the gods are melded into the group, sharing experience and knowledge, and when reincarnated take with them part of the group. The exchange of spirit causes the person to be different from what they were in their last life, meaning that there are never exact reincarnations of someone. The gods also change some in personality over time, as they are affected by the soul exchange, just much, much less than regular souls. Over time a spirit can grow enough in knowledge and experience that they splinter, splitting into multiple new souls, each with a piece of the knowledge that the original held.
In the time of the Bleed of Corruption the gods Kae, Draea, Sirran, and Sek’Malvent are less powerful due to the many followers they have in the living world. Sirrel, Labiir, and Sek’Torven are strong because of their lack of earthly followers.