What the game says
Only the Monster Manual describes the efreeti's spell-like ability to grant wishes, and then only in the vaguest terms, saying, "1/day—grant up to three wishes (to nongenies only)" (116). A great many official publications incorporate efreet to some degree or another, but an efreeti's ability to grant wishes seems to have never been mechanically defined. In fact, my search revealed only three published examples of wishes being granted.
- In 3e co-designer Monte Cook's Return to the Temple of Elemental Evil (June 2001), it may transpire that a "character holding the [special item] is
granted a limited wish. This can be done only once in a given week. [I]f [the special item is] left on the [surface]… no limited wish is granted" (118). So there's the word granted… just like in the description of the efreeti's spell-like ability. Further, context makes clear that no conditions are put on the limited wish's use—the creature can do whatever it wants with it. (I omit details here to prevent spoilers.)
- In 3.5-revision-mastermind Andy Collins's Lord of the Iron Fortress (Jan. 2002), one creature resists being the subject of certain effects "[t]hanks to some bargains with higher powers, as well as a carefully worded wish granted by [a] pit fiend" (4).
- In the Fiendish Codex II (Dec. 2006), in what is perhaps the stupidest ever recorded use of a wish that was likely made in all seriousness, a creature wards its totally mundane and comparatively inexpensive item "and everything within 20 feet of it with a permanent alarm spell, thanks to a wish granted by a blackmailed pit fiend" (132).
So while popular media tends to most often credit genies with granting wishes, only two Dungeons and Dragons 3e/3.5 incidents exist of creatures really having been granted wishes… and in each case the granter is a pit fiend! This is doubly odd as the pit fiend is technically unable to even grant wishes, instead having among its spell-like abilities the following: "Once per year a pit fiend can use wish as the spell (caster level 20th)" (MM 58). Because it's safe to assume that each pit fiend in the published example is not actually per se granting a wish but, instead, using its wish spell-like ability on the other creature's behalf, readers are left with only the first example—a series of events that leads to the granting of a limited wish—, and that's just not very helpful for determining how an efreet uses the spell-like ability grant up to three wishes (to nongenies only).
In other words, despite efreet being relatively common monsters that appear in literally dozens of publications as both opponents and uneasy allies, so far as I'm aware not even one efreeti is ever described in this edition as having used its wish-granting abilities. No NPC I could find in an official publication has, for instance, a special ability like Efreeti Slave: Bob the fighter can make 1 wish of the bitter efreeti who hangs on his every word or Wish: Bob the fighter has yet to make 1 wish that was granted him by an efreet. That is, there just aren't any more mechanics—or evidence of secret or intended mechanics—than just that lone entry of 1/day—grant up to three wishes (to nongenies only).
What the DM can do
So, really, the DM decides how a wish-granting creature grants wishes. There are at least two routes.
When a wish-granting creature agrees to grant a creature wishes, the wisher provides the wishes' details, and the granter, at the next available opportunity, must take the appropriate action to use its wish-granting ability to fulfill the wishes as detailed by the wisher. That's a bold attempt at mechanizing this, by the way; another DM may use different phrasing. Anyway, this solution is complicated and liable to lead to violence. Here's a scenario: An adventurer encounters an efreeti and has it on the ropes. So that she will spare the efreeti's life, the efreeti agrees to grant the adventurer three wishes. The adventurer utters the details of only two wishes. The efreeti takes a standard action and grants those two wishes.
Now what? The efreeti promised the adventurer three wishes, but she only made two, and he can only use his spell-like ability grant up to three wishes (to nongenies only) once per day. What's an efreeti to do? Follow that adventurer around until tomorrow—or even forever—until she finally offers up the details of that last wish? Or has the adventurer just foiled herself, giving the efreeti license to break their agreement by having detailed only two wishes when she could have—should have—detailed them all?
Let's go further and imagine that the adventurer is being followed around that same day by an efreeti anxiously awaiting the opportunity to fulfill that wish so it can get back to the City of Brass. Idly—during the same day her two wishes have been granted—the adventurer wishes for a turkey sandwich. If she makes no other wishes, has she foiled herself with her sandwich wish that will now be granted by the efreeti upon the next dawn? And do adventurers know all this, too, or is this DM-exclusive information?
And, to maintain verisimilitude, the DM should be consistent about this behavior and work out all of the kinks in advance, closing any loopholes that I missed… because the efreet certainly would have!
This reading seems in keeping with contemporary media's views on wishes as
Gygaxian Faustian tools that advance plots and that teach wishers to be careful what they wish for, but this DM can imagine brawls erupting at tables using this ruling (e.g. "I only wanted a +1 inherent bonus to Strength and some boots of speed not a morality lesson!"). Also, I suspect this ruling will result in many, many unhappy efreet.
When a wish-granting creature uses its ability to grant a creature wishes, the wisher gains the supernatural ability wish usable a number of times equal to wishes granted by the wish-granting creature. This ruling sidesteps the legal wrangling that occurs with the previous option, but makes efreet extremely vulnerable to their own wish-granting abilities.
By comparison, this even-more-mechanized wish-granting ruling sees the efreet on its turn take a standard action to use on another creature its spell-like ability grant up to three wishes (to nongenies only). However, that other creature will typically get a chance to use that supernatural ability wish prior to the efreet's escape. (With its locked-in caster level of 12 for its spell-like ability plane shift, a typical efreet can't ever take the feat Quicken Spell-like Ability (plane shift) (MM 304), for example.) This makes, for 1 round, the efreeti that granted the wishes immediately subject to the wishes that the creature makes, and, as many adventurers know, one round is all it takes for an encounter's tide to turn. Nonetheless, after the creature to whom the wishes have been granted takes her turn, the efreet can do whatever it wants on its own turn… including trying to just straight-up murder the wisher. (After all, this is D&D—that kind of stuff should happen to level 1 commoners who don't wish for the right stuff.)
What this DM would do
Unless the DM wants to roleplay the intricacies of extraplanar contract law—and I certainly won't yuck the yum of any who do—, I highly recommend the second option. Compared to the first option, this second option is just so much easier on the DM, the players, the adventurers, and even the efreet. It requires no mental gymnastics, no adjustments to the setting, and no significant house rules, nor must the DM write—and have his efreet slavishly obey!—a 10-volume set of The Etiquette of Wishes. If the DM just wants to have the PCs during an adventure encounter a darn efreeti, option 2's the way to go, and it's how I'd roll. Using option two also makes answering the questions much easier.
Can an efreeti convince a nongenie to whom it has granted one or more wishes to make wishes on the efreeti's behalf?
Probably… if the efreeti is very careful. This DM would have an efreeti who granted the wishes actually grant the wisher the spell-like ability wish, and an efreeti who somehow mind controlled a subject—perhaps the lucky efreeti's treasure includes a rod of rulership (Dungeon Master's Guide 236) (60,000 gp; 4 lbs.) or similar magic item—could command the subject to take a standard action to activate its special ability wish and make it on the efreeti's behalf. More likely is the efreeti convincing the wisher to use the wish on the efreeti's behalf via deception, a tack somewhat facilitated by the efreeti's spell-like and supernatural abilities. However, an efreeti is typically shockingly bad at impersonation and usually has no way of knowing, for example, how an adventurer's dead mother looked in life, and improper wish phrasing—like instead of the wisher wishing that you were free from your prison the wisher wishes that his mother were free from her prison—is liable to have grave and unforeseen consequences.
Combined, this sadly makes threats of violence likely the safest way for efreet to attempt to use their abilities to grant wishes that will, in turn, be used for their own benefit.
Can a granter opt not to fulfill a wish after the wisher makes it?
As detailed above, this DM would say no. As this DM would rule that a creature that's granted one or more wishes itself gains an equal number of iterations of one-use supernatural wish abilities, what the wisher then does with those wishes is beyond the granter's control. However, this DM can imagine a immeasurably long con by a conspiracy of otherwise adversarial wish-granting creatures to deceive the universe into thinking this is not the case and that, instead, wish-granters do have some control a granted wish's outcome, but that's more a campaign issue than a mechanical one.
This makes it risky for a lone creature to go around granting wishes, by the way. Like most magical effects where the user makes decisions about the results, there's no indication what will happen if the wish is finished before the wish is finished. (Also, this DM picked these to be specifically supernatural abilities deliberately so they're pretty hard to interrupt anyway.) An efreeti that strikes a bargain with a nongenie that then grants that nongenie wishes must trust the wisher not to renege… or get it in writing.
The inability of wish-granters to control the wishes they've granted neatly explains the many efreet that are stuck in situations that seem beneath creatures of such power. Because they can neither control the direction of the wishes they've granted nor opt not to fulfill the wishes after they've been made—making it either pointless or very dangerous for them to ever grant them—, the efreeti Falooz hangs out with a trouble-making gnome instead of the two of them ruling the universe (Book of Challenges 75–7), the efreeti duke Ajah-Kahar performs manual labor instead of cutting wish deals with his coworkers (Expedition to the Ruins of Greyhawk 117), the efreeti ninja Jalm D'akrar doesn't grant his already-powerful master a daily supply of three wishes (Dragons of Eberron 71–4), and the efreeti Razaor—reduced to helplessness by thorciasids—grants to the PCs that save him from otherwise certain doom only maybe a total of one wish (Epic Level Handbook 283). There's just no way for the granter to know how the wisher will use his newfound fabulous cosmic power.