[denethorthefirst]

What do we know about Radagast?

We know that he was one of the Istari, a Maia that was incarnated in a human body. That means that he was, for all intents and purposes, essentially human, although somewhat "supercharged": stronger, more endurance, powered by a superior spirit, blessed with otherworldly knowledge and magical power. But his human body restricted his spirit and his power in several respects: he had to rest, he needed nourishment, he could be harmed and even killed, and so on.

We also know that the Istari aged. In fact they aged rather rapidly, considering their origin and their mission (defeating Sauron, an immortal (!) warlord). When Saruman arrived in Lindon in 1000 T.A. he is described as a middle-aged man with black hair. But only 2000 years later, at the time of the War of the Ring, he appears as a very old man, his hair now completely white. 2000 years is a rather short time from a valinorean or elven perspective and I wonder what would have happened if Sauron had been a lot (a lot, lot, lot) more patient and if for example the War of the Ring had occurred in the year 8000 of the Third Age and not in 3018. If 2000 years were enough to completely age Saruman, then the Istari probably would have been dead or "faded" by then!

Back to Radagast. Tolkien fails to mention him at the end, that leaves two possibilities:
- he was either killed during the war in Mirkwood
- or he stayed in Middle-Earth after the defeat of Sauron.

If he stayed in Middle-Earth, what happened to him? He cant remain in his human body forever. It may take thousands of years, but he will eventually "die", i.e. his body will cease to function and his sprit will depart from it.
As we have seen when Gandalf and Saruman were killed, the incarnated Istari were not able to re-incarnate themselves. This seems to be somewhat of a rule in Ea. Once a naturally discarnate being (like an Ainu) becomes fully incarnated, the being becomes completely tied to that body and a destruction of that body is irreversible. Melkor, once he became incarnate after the theft of the Silmaril, knew that - thats why he was so afraid of combat. Only Sauron was able to circumvent that rule, when he was able to re-incarnate himself after his death during the Battle of Mount Doom - but that was only possible because the One Ring anchored him in the material world. And even then it took him over a thousand years.

So what would happen to Radagast after the eventual death of his body? He cant re-incarnate himself. Would the Valar intervene and bring him back to Valinor to rehouse him or return him to his natural state? I sure hope so, at least that is my head-canon. The alternative just seems too cruel.