You've been a villain all this time. And no one else. Here you were standing in front of him.
You were friends with Sherlock for a long time, he became softer towards you, he trusted you.It was good for you.You wanted to kill Sherlock and your plan worked - slowly but surely.
One day, when you were 'out on business,' Sherlock received a message from 'Moriarty,' "Come to an abandoned building on the outskirts of the city.Let's play? (:"
Sherlock, because of his addiction to solving the crime, of course went there.
He came in, inspecting the abandoned hall for traps or cannons.
Sherlock: "I'm here, Come out, Moriarty!"
Sherlock screamed, looking around for 'Moriarty'
The footsteps of his boots echoed through the building as he walked deeper into large hall. He heard laughter and looked up the stairs from which the laughter was coming.
He froze when he saw you there.