How would apping from the same canon be affected by the memory loss? Or rather - as they're regained would this call for certain memories or parts of them they just shouldn't get back, depending on how close the characters are?

To be specific, some guys I'm thinking of only know each other as opponents (and not even frequent ones), but they do play part in each other's history (and the development of one). Will this take some careful treading or is it a no-go from the start?