Swans
As he holds her hand things start falling into place.
Red John has fooled him once again, but it doesn't really matter right now.
They're still alive. And she's still there at his side.
He'd be truly and utterly lost without her.
She's going to be there for him, no matter what. He's so glad about that, though he's perfectly aware he doesn't deserve it at all.
Someday they're going to pick up on that awkward conversation they'd been having in their hideout in Las Vegas.
For the two of them are like swans. And swans do mate for life.