This isn’t a random thing: the player will encounter a certain character only if that character, during her adventures, has passed in that exact location at that exact time.
How it works is really simple: every time the player enters/exits a dungeon/building, the mod registers the exact building and the time he entered and exited.
When a character enters a building, the mod checks in its persistent file if another character was there at that time. If there’s one or more positive result, a billboard with the paperdoll texture is randomly generated.
In the first release I hope to make the paperdoll clickable to basic talk. In future release I was thinking of giving them more stats of the character they are based upon, like using greetings set by the player, given them affiliations based on theirs, maybe even to make them joinable NPCs.
In my wildest dreams, this could become a way to feel like a community even while playing. But then again, we all know that modders don’t play

There are a few issues I’m still trying to solve, but things are (slowly) coming into shape.