Duet

"Duet" is the fourth episode of the second season of Stargate: Atlantis.

Synopsis
After being scooped up by a Wraith Dart, Dr. Rodney McKay is rescued, but there isn't enough power to recover Lt. Laura Cadman. Soon, McKay realizes that Cadman's consciousness is inside of him, and the two have a hard time in co-existing. Ronon Dex makes himself at home in Atlantis.

Plot
While finishing up investigating the planet Thenora leveled by a Wraith attack, Dr. Rodney McKay and security team member Lt. Laura Cadman are scooped up into a Wraith Dart. However before the Dart can escape through the Stargate, Lt. Colonel John Sheppard and the rest of the team shoot it down to prevent the Wraith from learning that Atlantis was not destroyed. Sheppard reports back to Atlantis and has Dr. Radek Zelenka gate over to inspect the wreckage.

After inspecting the wreck, Zelenka discovers that the Wraith beaming device contains the signatures of two life-forms, but only enough power to rematerialize one of them. He forces Sheppard to choose a life form not knowing which is which, then activates the materializer, and McKay appears. The group returns to Atlantis, hoping that McKay will find a new way to power the Dart and retrieve Cadman. Then, however, McKay claims to hear Cadman's voice — from inside his own head. Somehow, her consciousness has been downloaded into his body along with his own.

While Zelenka works to repair the materializer, McKay and Cadman struggle to co-exist. After Cadman learns to control McKay's body, she can't resist making a few improvements — forcing him to exercise and giving him a woman's perspective on his big date with Dr. Katie Brown. McKay, however, is not even slightly amused.

Meanwhile, Sheppard introduces Ronon Dex to life in Atlantis. He quickly grows to respect the enigmatic warrior's incredible abilities both with weapons and in hand-to-hand combat. Eventually, Sheppard decides that Ronon belongs on the Atlantis team — but he'll have to persuade both Dr. Elizabeth Weir and Ronon himself that this is the right decision.

After Zelenka's latest attempt to repair the materializer fails, McKay and Cadman's situation grows dire — and not just because they're getting on each other's nerves. When they suffer a dangerous seizure, Dr. Carson Beckett informs them that the strain of containing two consciousnesses has become too great for McKay's body. One of them must voluntarily yield complete control to the other — and disappear forever — or they will both be lost.

Cadman insists that she has to be the one to go, partly because she is convinced that McKay will never do so, and partly because it keeps getting harder and harder to hold on. She starts to write a letter home, and requests that McKay deliver it himself, and explain what happened, the next time he goes to Earth. This gives him an idea: interface a gate control module with the dart to build a stable system. Just before Zelenka is to activate the beam, Cadman asks him to wait, and walks over and kisses Beckett passionately "just in case this doesn't work", an act which McKay finds quite repulsive, telling Zelenka "ugh, just hit it." After de- and rematerialization, both collapse, and are taken to the infirmary.

While they recuperate, Sheppard gets Weir's approval to include Ronon in his team.

When McKay wakes up, he hears Cadman's voice asking him if he is feeling better. He looks at the empty bed at his left, and fears that the separation did not work, in reality, she is in the bed on his right side. He tells her that he feels a little less crowded, a feeling she shares, pleased to have her own body back. Cadman is then congratulated by Sheppard, for surviving what would probably have been his worst nightmare.

At the very end, we see Beckett holding Cadman's hand in his, while smiling in a way that indicates that he shares at least some of what she feels for him.

Notable Quotes
(Sheppard and Teyla are talking about how all the wraith woke up)

Sheppard: Well, you said it yourself: too many Wraith woke up at the same time. Too many mouths to feed -- or ... hands to feed.

Beckett: You have a date Rodney? With a woman?

McKay: It is simply two adults sharing some friendly— Yes, with a woman!

(Sparks fly from a downed Wraith dart, causing Dr. Zelenka to jump in terror)

Sheppard: First time off world?

Zelenka: Yes.

Sheppard: Well, if there were any more Wraith, they would have attacked us by now.

Zelenka: Really?

Sheppard: If it makes you feel better. Did you find what we want?

Sheppard: Maybe there's something wrong with him an MRI wouldn't pick up, if you know what I mean.

McKay: I'm not crazy, I just have another consciousness in my brain.

Sheppard: So he just looks crazy?

McKay: I'm sure I do, but only because Dr. Fumbles McStupid here was in way over his head!

Zelenka: Yes! I made a mistake trying to save your life! Now, do you want to try and fix it, or do you want to continue to berate me some more?

McKay: I am perfectly capable of doing both at the same time.

Cadman: Consider the opportunity, right? To have a woman there with you, helping you out, feeding you lines. I really think you could learn something.

McKay: Thank you for the offer, Cyrano, but I think I'll pass.

McKay/Cadman: (the prelude to a kiss)Katie, I really like you. In fact, the past few months here have been made more liveable thanks to you. I wanted tonight to be special, but for reasons I can't go into now, I gotta leave. But I don't want you to be insulted or to wonder whether or not I am interested in you. Because I am ... I am very, very interested. See you soon.

(Two white mice had been de-materialized, and re-materialized as black cinders)

Sheppard: I'm no scientist, but those mice used to be a different color...

McKay: (to Cadman) Don't try to talk me out of this — I may very well listen.

Sheppard: Hold on, Rodney! I thought all the mice died?

McKay: Well, what are we — mice or men?

(McKay/Cadman is about to be dematerialized to separate Cadman's consciousness from McKay's body)

McKay/Cadman: (as Cadman) Wait. (walks over to Beckett and kisses him, causing the others to shift uncomfortably) Just in case it doesn't work. (McKay regains control and backs away in horror) Just... just... hit it!

Beckett: All of his vitals are stable. His body's reacting like it has been struck by a Wraith stunner.

Weir: So you think once the initial shock is over we'll have the old McKay back?

Beckett: I'm afraid so.

Sheppard: Lieutenant, way to survive what I think may be my worst nightmare.

Cadman: Thank you, sir!

McKay: Yes, thank you!

(John smiles at Rodney sarcastically)

Goofs

 * While talking with Ronon Dex, Dr. Elizabeth Weir refers to Lt. Colonel John Sheppard as a Major, even though it had been well over two months (by their perspective) since Sheppard had been promoted.
 * Lt. Laura Cadman is a member of the United States Marine Corps, but is seen wearing a black beret as are other members of the teams on the planet. The USMC does not issue berets of any color to any rank. Black berets are worn by non-Ranger/Special Forces/Airborne soldiers in the United States Army. They are also worn by Air Liaison Officers, Air Mobility Liaison Officers, and airmen of the Tactical Air Control Party in the United States Air Force.
 * While Sheppard is orientating Ronon on the FN P90 Personal Defense Weapon and the M9 pistol, the power cell for his Particle magnum disappears off of his belt in the few seconds between removing the Berreta's magazine, unholstering his magnum, firing a shot at the target, and reholstering it.
 * When Dr. Radek Zelenka jumps back when the Wraith Dart sparks, Sheppard then asks "First time off world?" in which Zelenka replies yes. This is incorrect because he would have gone off world when Atlantis was evacuated during the episodes "The Storm" and "The Eye".
 * In the opening, when the Dart is first approaching Dr. Carson Beckett, Dr. Rodney McKay and Cadman, Cadman tells McKay to, "Shut up!" When she tells McKay, "Stop speaking," and turns to face him, you can see her headset isn't behind her ear as it should be but to the front of it. After a quick camera shot of McKay and then Beckett, the camera is back on Lt. Cadman and her headset is now tucked behind her ear again.

Nominations

 * Nominated WGC Award for "Drama Series (One Hour)" (Martin Gero)

First appearances

 * Dr. Katie Brown
 * Lt. Laura Cadman