Doctor Harris was a Dakota-based physician.
Out of uncertainty about the long term effects of the Big Bang, Virgil visited Dr. Harris' clinic. In the initial interview, Dr. Harris tried to make sure the "changes" Virgil was going through weren't just puberty. Still puzzled as to why the boy wanted to be tested, he went ahead anyway to calm him down.
After the results came in, Dr. Harris informed Virgil that there was nothing wrong with him, aside from his electrolytes being unusually high. As that was normally caused by eating foods with a lot of salt and sodium, he advised Virgil to cut back on eating things like French fries and pizza for a little while.