That is really lovely of your Uncle but I can understand why your Brother would be skeptical. I think that it is a good idea that you go and seek help from an attorney and that you have a formal loan agreement drawn up.  The interest paid on the loan is tax deductible to you (or it should be) and the payments are an asset that is collectible.  The issue I have with giving any guidance here is not being able to read the power of attorney and ask why it is in place to begin with and if your brother makes decisions on your uncle's behalf at this point in time, since you say he is healthy and of sound mind.  The attorney will make sure that your brother is protected.  Good luck.