1. This is Moriarty.
2. He killed himself two years ago.
3. But then it turned out he might not have.
4. So where has he been?
5. Conspiracy 1: He did actually kiss Sherlock on the rooftop.
They faked both their deaths and spent two joyous years together before it went sour and they returned to normal life.
6. Conspiracy 2: He is still dead and it is a smoke screen by Mary.
Mary had Sherlock and Watson fooled all along and she really is a baddie. She is using Moriarty’s image as a trap.
7. Conspiracy 3: Derren Brown really was at the scene.
He was in on it and tricked Sherlock into thinking that Moriarty had killed himself.
8. Conspiracy 4: Mycroft kidnapped Moriarty and forced him to work for him.
Mycroft resuscitated Moriarty and kept him prisoner until he agreed to work for him.
9. Conspiracy 5: He was working with Magnusson and neither is dead.
He faked his own death and has been working with Magnusson to create a new stronger evil force. Magnusson didn’t die either.