You are assuming both that there is a minimum amount of time required before anyone can be "invested" in a character, PC or NPC, enough for their agency to override circumstances in the setting (that PCs meet and NPCs don't), and that all games are Neo-trad affairs where Players run their OCs with elaborate backstories and a special "main character" destiny, and therefore deserve special treatment in the "story" (at least that is the impression I'm getting from your post). Not every game is like that, and not every player places such investment in their PC that they can't allow them to be intimated, persuaded, or deceived, even if the circumstances in the setting strongly suggest otherwise, because the Player doesn't want them to be. To me, that violates the spirit of a game where playing your character as your character is supposed to be a big focus.