Izo's is sort of hard to pick, but out of every song that I relate to him, 'Hell Broke Luce' by Tom Waits seems to be the most fitting.
Maraka's theme is 'Momma Sed' by Puscifer, both as herself speaking to her son and her own mother speaking to her.
Vuduk's theme is 'Grand Canyon' by Puscifer. It doesn't entirely fit because she's a follower of the Way of Stone, but it still works as a semi-religious song dealing with one's own mortality; it could also work as her literally appealing to her (dead) mother.
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