It depends on what happens to the Scorched Hand. They might be subdued and captured, killed, or simply talked down. My party accidentally killed Idorii, downed and stabilised Velriana, and then managed to talk Khelru and Azaz into surrender. They then paid a druid to cast Reincarnate on Idorii, bringing her back but now as a human. But they didn't really keep them around after Book 1, and they parted ways after Book 2. I imagine Idorii wouldn't be too happy about being defeated, doubly so if there are fatalities, but could be won over and eventually brought on as a Cohort if your player takes the Leadership feat, or just as an NPC. There's certainly some quirks to her character to explore - she never knew her father, who was a wandering elf bard, and her mother was shamed by Idorii's birth and clear evidence of infidelity since the ears are a dead giveaway. That makes for a complicated psychological profile. She's also quite mercenary, just along for the money rather than any ideological loyalty, but (from memory) she does appreciate Azaz as a fellow outsider to the dedicated Nethysians Khelru and Velriana. Agreeing to bring her back, even as they handed Velriana over to the Pharasmins, is what cemented Khelru and Azaz's genial relations for my players.