So my PCs traded a wish for "a big favour" of an efreeti (who is a minor noble in the brass city). The wish wasn't over the top, it was to resurrect their friend.  And the efreeti, at the time, was at their mercy since they had promised to free him, but the wish came later.

I can probably pickup any random adventure/module from the OSR or any other edition of D&D but keen for it to be efreeti/Arabia themed if possible.  Any suggestions? My first thought was Arabian Nights from 2e but I am not familiar with that setting so not sure what adventure is good or not (working through the synopsis of some now).

Any advice from the RPG brain trust?

I'll be running it in 5e but happy to convert older adventures or OSR stuff (in fact, thats pretty much all I do these day, dont touch wotc 5e stuff).

Thanks.

How about adventure 7 in ALQ3 A Dozen and One Adventures for AD&D 2nd Edition Al-Qadim, «The Djinni's Lover»?

Quote
Diliram once considered herself the happiest djinni in the world, living in harmonious bliss with her lover Namered in the Genies' Garden, located deep in the wilderness of the Haunted Lands. One day, the lovers were surprised by a sha'ir named Shafazal, who carried an ancient and powerful genie prison crafted in the shape of an astrolabe. In the blink of an eye Namered was gone, trapped within the magical device, leaving Diliram to confront the mysterious sha'ir alone. Turning herself invisible, Diliram flew into the air and hid behind a cloud before the sha'ir could trap her as well. Diliram watched from the sky in horror as Shafazal summoned her lover from the astrolabe and commanded him to carry her home. Namered obeyed at once, bearing Shafazal back to the wizard's oasis.

During the past few days, Diliram has been invisibly spying on the oasis and the wizard's formidable guardians. At first, the genie bided her time, fearing the power of Shafazal and her powerful allies. Slowly, her burning anger and jealousy have grown unbearable. She cannot remain idle while a mortal woman who has stolen her lover remains unpunished. It wasn't long before Diliram decided to enlist a group of mortals to her cause. Diliram is looking for a group of honorable adventurers when she encounters the PCs.

Sure, you have an Efreet, not a Djinni, and your Efreet seems to have been trapped for a while in a bottle, ring, sandal or some other random object; but then it's relatively simple to adapt Namered to be your Efreet's relative rather than lover, and perhaps you need to obtain it from the Sha'ira's descendants rather than from the Sha'ira herself.

Pathfinder 1E had the Legacy of Fire adventure path, which had a rogue efreet trading wishes to increase his personal power so that he could try to court the demigoddess queen of fire elementals.

There's also a bit in PF1's Ultimate Magic talking about things you can use in a Planar Binding to encourage the target to see things your way. Powerful weapons and attractive humanoid slaves are suggested for efreeti.

Beyond that, a 'favor' is a pretty flexible thing. Kill (or capture) a rival, humble an opponent (how about a heist in the City of Brass?), act as a messenger/courier into dangerous terrain... consider what a modern day crime lord might do. Heck, watch some mafia movies, that might be good inspiration.

1; A hunt-and-kill mission against a wizard that is making preparations to bind another effeeti to servitude (with the proviso that if the efreeti has been bound before the party arrives, they are to free it without demanding payment from it).  You can position the wizard in your Arabia-equivalent in the campaign world, and have the efreeti helpfully provide transport there if needed.  (Bonus points if the PCs note that he's not promising a return trip for free.)

2: A raid on either an undersea group (sahuaguin, merfolk, etc.) to recover a specific treasure, or perhaps (if the PCs are beefy) an attack on a marid in its lair.  The idea is that this is something that the efreeti can't easily do himself (and while PCs probably can't breathe underwater, they're less-disadvantaged there than a creature of elemental fire.) This is most suitable if the PCs already have Water Breathing and the like set up.

3: The PCs need to entertain / help serve at a celebratory feast that the efreeti is throwing to celebrate their freedom (and demonstrate to their efreeti peers that they still have their shit together and that binding was a fluke, nothing more).  The given subtext is that the efreeti being waited on by his liberators demonstrates that you have no lingering hold over him.  This can just be a fun social encounter, or one of the efreeti's enemies can try to attack at their feast to stop them from re-entering the efreeti social ranks.  This is good because it can be done quickly and with no logistic challenges; the efreeti whisks the PCs to their domain and provides elemental protection, drills them on etiquette, and you run the social encounter (with or without ambush), with the PCs being re-deposited where they were after, but you'll need to make up some fancy efreeti culture stuff.

4: You might throw something morally-ambiguous there.  IMC, it's a thing that genies of all kinds, even the Good ones, have bondage and slavery built into them on a fundamental level, and that even the CG djinni interpret that by giving their slaves the most relative freedom and good treatment, and eventual paths out of slavery for those unsuited to it.  Barring very rare exceptions who are not representative of their kind, a genie of any kind freed from bondage will seek to capture others, which makes a good conundrum for any goodly person who objects to slavery on principle.  Having the efreeti throw them a softball favor of recapturing a favored slave that they lost track of in their own captivity could throw a moral question at the party.

5: You can always have the efreeti be entirely unreasonable and have the 'favor' be a set-up to dispose of the PCs, as the efreeti finds owing their freedom to mortals an intolerable slight to their pride, and have the thing turn into a quest to hunt down the

I've been writing a Dark Sun / Desert Dungeon Crawl RPG which is all about interacting with various genies who definitely WANT something for wishes.

In the setting, the granting of wishes is part of an extremely dark scheme of revenge on the human race for the destruction of an ancient demon worshipping kingdom.

Thanks for the advice all. I'll check that adventure as well.  I was actually thinking of linking him to the efreeti on hot spring island - a miscreant nephew who has bankrupted him while he was capcivity.  PCs are to retrieve him and re-open operations.  But it's probably pretty in-depth for a "favour".  Though the PCs DID leave it that open ended.

I also like the social encounter thingy.