Something bad happens to Sherlock, and he has to be sent to the hospital. John finds out about it, rushes there, only to wait outside his room. He heard from the nurse that he can go in now, but that Sherlock's 'boyfriend' is in the room. Curious and jealous, he enters the room to see Victor holding Sherlock's hand, while Sherlock is unconscious. He looks over at John as John says "Who are you?" and he starts to say something but then Sherlock whispers "Victor,". And that's how season 4 ends.