The plot (or lack thereof?) thickens! Based upon my research (which may or may not involve having read a tonne of manga), it's generally frowned upon if not outright against rules for a teacher and student to be too friendly. It makes sense, because a teacher shouldn't be biased towards a particular student. However, can you really blame Madoka? She's kind of between a rock and a hard place after all.

Oh, and yes! Seiko's brother has a name now! The name "Senou" [seh-no-ooh] is an Engrish variant of "Senoo" which is short for "Seiko No Ototo", literally "Seiko's little brother". It also sounds like "snow". Spoilers?