Sounds like
Radagast didn't get around much. In
Fellowship it describes how he found
Gandalf not far from
Bree and said to him "All I knew was that you might be found in a wild region with the uncouth name of
Shire". He had no idea where or what
the Shire was and didn't seem too happy about having to
travel far to find Gandalf.
He then gave Gandalf the message that he needed to go see
Saruman. Gandalf told Radagast that his help would be needed and to send out messages about what was happening to the
birds and beasts. Radagast did so and as a direct result Gandalf was rescued from the top of
Orthanc by
Gwaihir the Windlord.
At the
Council of Elrond Gandalf tells everyone that after speaking with him, Radagast rode off to
Mirkwood to spread the word. The Eagle came looking for Gandalf to give him a message, found him on top of the tower and rescued him.
One thing that is apparent is that at no time is Radagast portrayed as
evil or in league with evil. Quite the opposite. If anything he comes off as somewhat naive, honest and trusting.
One can only assume that Radagast did indeed play some part in the
War of the Ring. Many did and weren't mentioned in the book. The
battles of the
Lonely Mountain and
Dale, Mirkwood, etc could be a book in itself. Perhaps Radagast helped the
Wood Elves or
Dwarves at some point. Who knows?
