Can my Small Aether Elemental summon throw my very small PC ally around in Pathfinder?
And if so how far?
In other words, how does Telekinetic Throw work with willing creatures?
The Small Aether Elemental's offensive abilities lists the following:
Ranged telekinetic throw +5 (1d8+2)
Special Attacks telekinetic maneuver, telekinetic throw (DC 12)
And their extraordinary ability Telekinetic Throw says:
An aether elemental can fling a creature or object (with a maximum range of 480 feet). A creature receives a Fortitude save to avoid being thrown (the save DC is Constitution-based). The telekinetic throw deals the listed damage to both the thrown creature or object and the target.
The aether elemental can throw a creature or object that weighs at most 50 pounds per Hit Die the elemental possesses.
Suppose the elemental tries to throw your small PC ally. First we check the weight - the elemental has 2 HD, so it can throw a creature or object weighing up to 100 lb.
If the PC ally weighs less than 100 lb, then they make a DC 12 Fortitude save (as Wyrmwood's answer says, they can choose to fail the save).
If they fail the save, the elemental then makes a ranged attack with a +5 bonus against a target (or location) within 480 feet. Empty locations have an effective AC of 5; it's the AC used for throwing a splash weapon at a square and is the same AC as a creature with 0 Dexterity.
Upon hitting the target, the PC then takes 1d8+2 damage. If the target is a creature, then it also takes 1d8+2 damage.
If the ranged attack roll fails, it's not entirely clear what happens to the PC projectile. The GM could use the splash weapon rules, and randomly select a square adjacent to the intended target, and have the PC land there.
You can voluntarily give up a saving throw.
A creature can voluntarily forego a saving throw and willingly accept a spell’s result. Even a character with a special resistance to magic can suppress this quality.
If the Small aether elemental has been brought forth by an effect like the spell summon monster, then, unless the summoner can issue the aether elemental alternative commands in one of the aether elemental's languages—Aquan, Auran, Ignan, Terran—, all the aether elemental will do is attack the summoner's enemies. (The summon monster spells say that a summoned monster "attacks your opponents to the best of its ability[, but i]f you can communicate with the creature, you can direct it not to attack, to attack particular enemies, or to perform other actions.") Without being issued other orders in one of its languages by its summoner, the aether elemental won't huck your ally unless the aether elemental perceives the ally as an enemy, and even then only if that would be its best option at that moment.
Once the order has been issued to the aether elemental to throw the ally, then the aether elemental must get adjacent to the ally that's to be thrown. Even though the extraordinary ability telekinetic throw can hurl a creature or object some distance, no range is listed for the ability telekinetic throw itself. (This reader thinks that the lack of a range on this ability may be an oversight. A GM may consider a house rule that gives the ability a range anyway—perhaps long (400 ft. +40 ft. per 2 Hit Dice of the of the aether elemental) as if it were similar to a spell-like ability like the telekinesis spell.)
After the aether elemental becomes adjacent to the ally, the aether elemental takes a standard action to employ its extraordinary ability telekinetic throw against the ally. Here the GM has at least two choices. On Magic on Saving Throws says, "A creature can voluntarily forego a saving throw and willingly accept a spell's result," but that is for spells… and, presumably, at least other magical effects like spell-like abilities and supernatural abilities.
However, the GM may decide that a creature can't voluntarily forego a saving throw against merely natural and even extraordinary abilities, as those aren't magical. The GM may justify such a decision with something like, "Even a Pathfinder human can't elect to become infected when exposed to the disease filth fever, can't opt to be dealt the damage after mistaking for hand sanitizer black lotus extract poison, or choose instantaneously to fall deliberately into the pit trap."
In other words, ask the GM if voluntarily foregoing a saving throw against a mundane effect is allowed. Then pick the appropriate course from those below:
If the GM rules that a creature can voluntarily forego its saving throw against the extraordinary ability telekinetic throw, then the ally can forego that saving throw so as to become the effect's subject.
If the GM rules that a creature can't voluntarily forego its saving throw against the extraordinary ability telekinetic throw, then the ally must attempt that saving throw. (The potential subject that wants to be thrown, of course, can exercise any available options that penalize this saving throw to make failure easier.) If the potential subject succeeds on the saving throw then it's not thrown. If the potential subject succeeds on the saving throw the it's thrown. (And it's no longer a potential subject.)
Then, once the ally's the subject of the ability telekinetic throw, the aether elemental—as part of the same standard action it took to employ the ability telekinetic throw—makes a ranged attack roll against a target that's within 480 ft. Success means that both target and subject are dealt 1d8+2 points of damage. Failure means that the attack—including the ally!—misses.
This GM would have a miss put the subject in the in the nearest unoccupied space to the target but, of course, not have the ability telekinetic throw deal the subject or target any damage. (Though damage could still result from a 480 ft. fall!) As this fine answer explains, a point in space can be a pretty easy target (usually AC 5), and another GM may instead use the rules for off-target splash weapons to determine where the subject lands.
The GM should also decide whether a thrown creature after it's been thrown is automatically rendered prone, attempts a saving throw to avoid becoming prone (perhaps Ref DC 12 similar to the original effect?), or can make an Acrobatics skill check to avoid becoming prone (maybe DC 15?). Alternatively, a GM may grouse that this has already become way too complicated and rule that anybody who's the subject of an aether elemental's extraordinary ability telekinetic throw somehow remains upright afterward because, at this point, whatever.
Note: This GM usually urges players have their PCs stick to air, earth, fire, and water elementals when their PCs bring forth elementals by casting summon monster and summon nature's ally spells lest foes also Dumpster-dive for unusual elementals; whether other elementals (like aether elementals) can or can't be summoned at all is the subject of this question.
The 480 foot range is the range that you can manifest the spell, not the range you can throw. This is consistent with the "long" range for a level 2 caster. If this were not the case, you could throw anyone upward 480 feet for 20d6 (max) fall damage. Or just moving an enemy 480 feet away would be incredibly powerful at that level (good luck getting back over here before i've slaughtered your allies).
Unfortunately, there's not a lot in the description of how far you can throw, but it does have the "Telekinetic Manuever" ability. Make a CMD check, using the Telekinetic Manuever ability for your CMB. Some groups have houserules about using a combat manuever on a willing target, where they can forego their defense. Either way, make a CMB check against their CMD, and if you beat it, you move them 1 square + 1 for every 5 you beat the CMD by. Make a touch attack if this includes slamming them into another creature.