If you draw up a “lease,” chances are you will find a “lessor” and a “lessee” inside. Someone who “abducts” is an “abductor,” and the victim is an “abductee.” English has lots of pairs in which one is a “do-er” and the other a “do-ee.”
If you “inherit” something, you are the “inheritor”; there is no word “inheritee,” for the person giving or the person getting.
In fact, when it comes to leaving something behind when you die, not many word pairs share the same root for the giver and the receiver. (Like “give” and “receive,” which are different words for opposite actions.)
A rich uncle can be the “bequeather” who “bequeaths” a “bequest,” “bequestment,” or “bequeathal,” but the noun for the lucky person who gets all that “bequeathable” stuff won’t have any “quest” in it at all. (Though all that $$$$ might pay for lots of other kinds of “quests.”)
That person might be an “heir,” and what he receives is an “inheritance,” which at least has the same roots as “heir.” Another noun for the loot, “heirage,” showed up around 1478, according to The Oxford English Dictionary, but quickly vanished. You won’t often hear someone called an “inheritor,” though that’s a perfectly legitimate word, too, first heard around 1433.
The person who “inherits” is also a “beneficiary,” and the rich uncle might be a “benefactor.” Of course, someone can “benefit” before the rich uncle dies, so it’s less precise. “Inherit” inherently includes the idea of death.
You don’t have to be dead to pass along a “legacy”—just ask all of the “legacy” media like print newspapers. If you receive that “legacy,” you might also be called a “legatee.” (Or, in newspaper parlance, a “subscriber.”) But in ancient times, “legacy” had two meanings: “The action or an act of bequeathing,” like an inheritance, according to the OED, first used in 1485, and a slightly earlier meaning, from 1384: “The function or office of a delegate or deputy.” Even today, the Catholic Church has “legates,” or papal ambassadors. And yes, they’re all related to the roots of “legal.”
An “heir-in-waiting” might also be called a “scion,” which was a popular word even before Toyota started making a car by that name in 2003. Children following in the footsteps of wealthy or successful parents are often called “scions,” though the usage is almost always applied to a male child, not female.
“Scion” also literally means an offshoot, a young tip or branch of a plant. Both meanings were particularly appropriate for Toyota, which marketed its car to appeal to younger people—the next generation of Toyota buyers-to-be, or, pardon the expression, “Scions” for “scions.” Toyota is killing the brand in 2016, “bequeathing” the name only to the human “scions” rolling in the green.