Ishren is a Shin truthless who is indentured to someone in the Diagram organization. He was involved in some kind of plot to get Kael away the rest of the party when they infiltrated King Taravangian’s palace.
He told Kael that a new owner holds his oath stone every night, and he is unsure who is his master on a day-to-day basis. He asked Kael to “free” him from his hell and started a fight with him - presumably under orders from his master of the day.