Sally, no worries. If nothing else, having only the overall idea or, even, (and I'd never expect myself to say that
) knowing at least the movie portrayal of the characters would be sufficient (however, I hasten to point out that this is a concession, not a rule! Whoever has read LotR more than once has no excuse from me!!!
). And personally I think Théodred is a very good pick - and as there's only very little about him in the books, you are not bound much by any character specifications. And I believe Saruman would like to add Théodred to the Fellowship, as kind of a "remedy", to show good face to Théoden (and even Théodred himself).
And only one warning - I think that it's not necessary to point that out, but just to mention it - while in-character issues with other characters inevitably have their place here, this is still a WW game and don't let the roleplaying slip out of hand; you still suspect those you suspect in real. But like I said, there is sure no need to mention that.
Oh, and welcome aboard,
Gwathagor! I will sign you up as Halbarad with a question mark, you can still change if you wish.
Btw, I am getting the feeling that the consistency of the Fellowship begins to somewhat resemble the Grey Company. Is that saying something about the nature of this alternative Fellowship?