Next door neighbour

The neighbour next door came and say hello. He has been here, in the department, before the term started. We normally just say the perfunctory hi-s and hello-s or smile when we meet at the corridor. But today..he came and introduced himself. Not sure where he originates from, but from the name, he is certainly not British (I am sure he is not Russian either like the neighbour down the other door, whom I still apply the theory of perfunctory conduct with). Coincidentally, H is doing biology. Mathematical biology that is. And when he knew i was doing something in that area. He was asking me this and that and ...I was grappling ok.. Boy, he sure knows his stuff. Which reminds me, maybe I need to brush up on mine la.