THINGS I WANT IN FUTURE SHADOWHUNTER BOOKS:
  • SIMON TO BECOME A SHADOWHUNTER
  • SIMON AND CLARY TO BECOME PARABATAI
  • SIMON AND IZZY TO GET MARRIED
  • MAGNUS AND ALEC TO GET MARRIED
  • JACE AND CLARY TO GET MARRIED
  • TESSA AND JEM TO GET MARRIED
  • JULES AND EMMA TO DEFY CLAVEY PARABATAI LAWS AND STILL BE TOGETHER OR SOMETHING
  • JACE TO REALIZE TESSA IS HIS GREAT-TO-WHATEVER-DEGREE GRANDMA
  • JACE TO REALIZE BROTHER ZACHARIAH IS ACTUALLY THIS RAD LITTLE SHADOWHUNTER NAMED JEM CARSTAIRS WHO WAS HIS GREAT-TO-WHATEVER-DEGREE GRANDPA’S PARABATAI
  • JACE TO REALIZE THAT TESSA AND WILL, LIKE HE AND CLARY, FIRST HAD SEX IN A CAVE
  • JACE TO REALIZE HIS DUCK HATE IS HEREDITARY
Guys I've got it

When Gatiss said Molly was like moving wallpaper, he gave away exactly what he had planned for S4. Much like in the movie Sherlock Holmes: A Game of Shadows where Holmes uses an odd suit to blend in with the background like so:

image

I have a feeling Sherlock is going to force Molly into one of these suits, one that looks exactly like his wallpaper, this way he can protect her since Moriarty is back. It all makes sense now!