User blog comment:Zathronas/Speculative author: Who is Summer Rose?/@comment-11346598-20140809050717

Personally, I think Summer, Ozpin, and possibly some others were facing a large Grimm force. Summer gives her life to stop the Grimm, which is why Ruby hero worships her, and because Ozpin was their when she died he took a personal interest in Ruby. Maybe because Ruby reminds Ozpin so much of Summer, his close friend.