[Rumil]

Ok, Shadow,

Radagast was a Maiar from Valinor (can't remember his name but I'm sure someone will). When Gandalf, Saruman and the Blue Wizards were sent to Middle Earth, Yavanna insisted that someone was sent to look after the vegetation and animals, so Radagast was sent. He lived at Rhosgobel, in the South of Mirkwood, not too far from Dol Guldur, there's a theory that he was responsible for holding Sauron's power in check during the time when he presented himself as the Necromancer.

Tolkien says that only Gandalf of the five wizards stayed faithful to his mission, implying that Radagast failed in some way. I think this is a bit harsh on Radagast as he was supposed to be concerned with the animals and plants, not the elves and men. Basically, he was the first environmentalist.

In relation to his misleading of Gandalf, there was no reason to punish him as he acted in good faith. As far as Radagast knew, Saruman was trustworthy, Saruman gave Radagast the message for Gandalf, so Radagast can't be blamed for Gandalf's subsequent imprisonment. Indeed, Radagast provided Gandalf's means of escape from Orthanc as he saw no reason why the Eagles shouldn't be sent there to report. This of course subsequently saved Gandalf.

There's another theory that Radagast had a special relationship with the Eagles, so was responsible for saving the day at the Battle of the Five Armies and at Mount Doom. However, I reckon Manwe had a hand in all of that.