Serileni led the Waterdark order's shadow-arm, the darkness adepts Kareshi had raised inside the order and then, when the kingdom came looking for an answer, gave away. Of all the order's people, Serileni's were the ones whose work had run closest to the souring of the bonds, and that was enough. After the Severing, Adron struck Serileni's faction from the house-rolls, stripped them of name and ground, and put them outside the kingdom for good. The bill of exile kept at Adrak begins with Serileni's name and runs on through a list of plain Nagashi struck through in a single hand.
Stateless, owed nothing and owing nothing, the exiles took up the only trade that would still have them, which was contract killing and the quiet work that travels with it, and Serileni is named the first master of it. The cells that sell that work across the Middle Sea today trace their line back to that founding by their own reckoning, and they have never stopped reckoning Adron's banking houses as the people who sold their founder to save themselves. The myth that came later made Serileni something else: the obsidian blood returned, the Megélren traitor cast out for the scale he was born with. He was not. Serileni was scaled like any banking house's child, and the black-scaled form that the present hangs on his name had nothing to do with the Exile and nothing to do with him.