OKAY, CAN WE TALK ABOUT THIS FOR A SECOND?
Moriarty is in Sherlock’s Mind Palace. CHAINED UP, IN SHERLOCK’S BLOODY MIND PALACE.
Not only did Sherlock fully accept the whole “I am you” “You’re me” conversation that they had, he recognizes it IN HIMSELF that there is a part of him that truly is Moriarty.
AND HE CHAINED IT UP.