Season 7, episode 15 "The Red Band" (the penultimate episode of the entire show)

After letting emotions run fly, Jane, finally back on his feet after the incident 2 years ago, can't hold it in anymore.  He's more determined than ever to solve the case because he has to speak his mind. And after charmingly revealing the killer of the episode with his usual touch of wit (It turned out to be the deranged sister-in-law of the victim for monetary motives) He demands to speak with Teresa immediately.

It's late at night. Full moon.
They're in his attic upstairs. Alone.
Jane becomes nostalgic and brings up the best of times with her. Eventually he concludes he still has cares for his long-lost family but it's not that kind of love anymore; it's spiritual.
He knows that it's now ok to express romantic feelings to another woman other than his beloved wife.
Lisbon is taken aback understandably, not quite sure what to do.
Jane declares his love for her right there and then. It's always been there since day 1 but he admits his feelings have grown immensely in the past weeks.
He takes her. One hand on her pelvis and the other on the jugular. Staring. Caressing. Never has there been such an unawkward moment between them with this amount of tension and silence. It's real. They're in the moment. He moves from her neck to her eyebrows, and eventually strokes her perfect zygomatic arch. They're a breath apart.
He kisses her. Just kisses her. Like teenage crushes for the first time. [commercial break]

Lisbon is helpless; frozen with butterflies. Patrick, drawing away, utters those three words and tells her he needs some time alone now. 
Feeling unsure of his actions he returns home to seek guidance or an epiphany of sorts to confirm if his wife is ok with this. And as per, he boils the kettle to spark the hallucinogenics he requires.

Meanwhile Teresa is still lovestruck in her office. It's nearly midnight and no one is in the CBI headquarters - or so it seems.
[enter Ray Haffner] (RJ disciple presumed dead since the explosion 2 years ago)
He's fuming. Ropable. But contained enough to speak with her.
He explains how his almighty mentor cut him a deal to keep him alive during the explosion and how he gave up his "life" over his lust for Teresa - all for Red John. He's been stalking her nearly every day and has only grown in his love for her. She's defenseless, and after tussling with Ray (breaking his Visualize band), she is forced back to Haffner's house.
He ties her up and begins pondering the life they could have had together and not with Patrick and all is patheticness. 

All this is happening while Jane is reaching his delusions and is communicating with his wife. She is ok with the idea of their relationship and leaves Patrick with a final message to "go see her now - she needs you, my dear Patrick". Questioning the reality of what just happened, Jane always goes with the flow and begins to look for Lisbon who is absent at headquarters. As he anxiously leaves he finds a broken Visualize band. He puts two and two together and realise she is grave danger. 

Now Jane thinks quickly and phones former Agent Van Pelt who still happens to have the computer skills necessary to track down the location of Lisbon. And within 10 minutes he arrives at Haffner's house. He breaks down the door and pulls his gun on Haffner who has taken advantage of a bloodied and bruised Lisbon. *BANG*
*soft, eerie, unquestionable voice* 
"I thought we agreed for you to lay low, Haffner. It's a real shame - you were my best servant"
Red John lowers his gun but Patrick still has back turned to the door.
Patrick tries to slowly turn his head until he is intervened 
"up-pupupp.. Patrick, you turn around when I want you to turn around. Understand?"
Patrick, a midst the fear, has a sly grin on his face because he finally just realised the true identity of his good friend. 

"What's the matter, Patrick? Cat got your tongue? Nevermind that. How about you meet me alone at this location in 20 minutes." *slides up behind Jane and slips a piece of paper in his jacket pocket*
"I know you'll be alone because we have such great mutual respect for each other, isn't that right, Patrick?" 
And after whispering another William Blake reference in his ear, he playfully slaps Jane twice on the cheek with the infamous rubber glove before leaving. 
FIN.
Commence episode 16, the ultimate episode, titled "The Red Showdown"...