"I figured." When he'd seen Sherlock coming back alone, he'd known it. That doesn't mean it's sunk in yet. He's still processing the death of the man next to him, and doesn't know yet how to cope with the only other person he truly trusts here also being gone. Where does this leave him?

He uses the gingerbread wall as support and stands up, fixing the eyepatch on. It's a bit too big, a little slack, but it's better than nothing. His mouth keeps moving wordlessly, as if he's trying to form the right words to explain why the tears have streamed a little faster since Sherlock delivered the news.

What he finally settles on is "I'm sorry."