At first I was thrown by how little Ollivander seemed to judge Snape, although he knew about the Dark Mark - but by the end of that first section his characterisation made perfect sense to me. I love the way you draw their relationship...and to bring it to post-DH was a lovely surprise! Yes, I can well believe that Severus is now old enough to be interesting to Ollivander. A lovely, convincing story that extrapolates nicely from canon!