Keeping Up Appearances

Everyone knows Tonks and Lupin got married, right? Well... what if they actually didn't? What if Teddy isn't even Lupin's son? What if, when Tonks and Charlie started dating something happened that made them hide everything in an elaborate web so that everyone would THINK that they barely knew each other? Follow me down the rabbit hole. [NT/CW (ImpRL/SB later in the story)]