Now that this student is here, s/he is sticking to this other area of interest. This is all fine and dandy, but I really wanted an RA who would also work with me as a thesis advisor and work on a thesis related to this grant. This puts me in an awkward situation. I do not believe in forcing grad students to do thesis projects that they are not interested in, so if the student wants to work in this other area that's fine, but I won't get as much out of his/her work for the project. I have money to fund a student for two years, but s/he isn't doing a thesis related to the project, I feel like I'd rather find someone else for next year. This is also not ideal, because I would have to train the new person later. I also hate to tell this student that s/he won't have an RA next year if s/he isn't going to do a thesis related to the project (s/he would still have a TA). I don't even know if my RA knows that s/he was last-minute replacement and I hate to share that, but this is really a problem.
Any ideas? Help!
ETA: I had a talk with RA this morning and I think we are on the same page now. S/he is willing to do a thesis connected with the project and this doesn't exclude the other area s/he had been talking about. I am feeling much better about things now. I think s/he will be a good student!