So the basic idea of this is that Ozpin and Salem have a past together. Not saying that their relationship was a romantic one but that they were once close to each other. I mean the way they talked to each other in the opening monologue in chapter one of volume one and the way the two sorta talked at the end of volume three (it's complicated). Also the way she says Ozpin's name when talking about him either to others or to herself I think that they were once close either as friends or something more. Which leads me to my next two ideas...