If two players would like to make paired characters for this, what would be the best way to go about it in light of the fugue state being a thing? Early memories ala childhood or adolescence with the last few years a mystery? Nothing at all but a vague feeling of, 'I know this person, somehow'?
If you want to avoid the subconscious flashes, have both characters just start with matching items and have them automatically notice them. Maybe they are Varisians with similar kapenia scarves. Maybe they have lockets with the same pictures inside. Perhaps both carry swords with praising inscriptions for the same deity or ancestor. Mass production is rare enough on Golarion to implicate a link between two persons with similar stuff.
I'll be starting with Nameless One as my 1st level feat (paid for by the Rich Parents trait) with a Plague Doctor mask.
"The Misbegotten" will be in the interesting position of not being able to reveal too much about his past while also being terrified of whether it was revealed in the years he can't recall.