[Sophrosyne]

I don't think it's weird, but like the others said, you have to be aware of laws for once the senior turns 18, and having the same level of maturity as each other. You also have to make sure that the sophomore isn't just doing it for the attention and popularity, and the senior isn't doing it just to have authority over a person. A lot of factors come into school relationships, but overall it isn't weird or unacceptable.