Here's my preliminary take.
[ ] Plan: Take what we need
- [ ] ELF: Extradite him to Ulthuan. (+???)
- [ ] SKAVEN: Claim him.
- [ ] PUPS: Cede them.
- [ ] OOZE: Sell it to the Imperial Zoo. (+wealth)
- [ ] AXE: Split it.
- [ ] BOOK: Hand it over to the Dwarves. (Dwarf favour)
- [ ] GOLD: Split it.
Elf may or may not be some pirate prince or something, but either way, they're the professionals for dealing with the Naggarothians--and this one was very far from home and relatively intact (And thus, likely not a prisoner)--so he's likely to be of considerable interest to Asur intelligencers while of relatively limited interest to us (One of the white whales the Skaven chase are penetrating Ulthuan and getting a presence there, if this guy might have been facilitating an attempt of theirs to get a foothold...). The Skaven is a wealth of potential intelligence on the Eight Peaks campaign, since it seems he was the loser of a recent leadership duel, and his knowledge of Khazalid is enough that he's likely local. Beyond that? He promised to serve us, and while he'll betray that if he thinks he can get away with it, we can squeeze him first, and he's liable to play along for a good while because the food's probably better than he's had in years and we're unlikely to go too hard in the torture if he cooperates--and he'd know that full well too.
The pups are cute and Johann seems to like them so he can keep them, the Ooze seems like a curiosity more than anything else, but it should be valuable for the Imperial Zoo--lord knows, a waste disposal creature would probably be useful for keeping things clean for them. The book is something that we want to make sure gets appropriately buried, so Belegar gets to decide what to do with it, and the axe and gold were a joint effort, so splitting credit is what is right and proper.