This would also work for characters who know of someone, but haven't met them! They may remember hearing this person's name mentioned, for example, but the clash might occur where this person acts in a way where they've known other characters for months or even years.

i.e. For Aster, plenty of friends may know Reno, but act as if they've only just met him, despite Aster's dream having him play a very constant presence in her life.