Stargate Atlantis/Recap/S03 E08 McKay and Mrs. Miller

"I solved your problem in my spare time... with finger paints."

- Jeannie Miller, nee McKay

McKay is urgently needed back on Earth - Carter has a problem only he can solve. That problem turns out to be named Jeannie Miller, McKay's estranged younger sister. It turns out that she has solved the problem of extracting vacuum energy from a parallel universe in her free time with her daughter's finger paints - the same problem that lead to McKay blowing up a solar system last season. The trouble is she's Happily Married and has absolutely no interest in signing a confidentiality agreement that will make her work the protected property of the US Military.

McKay manages convince her to come back to Atlantis with him, but not before she reveals that his first name is in fact Meredith. They call ahead to Zelenka to get everything at Atlantis prepped by the time they get there. (Nobody seems to raise the question of whether running the solar-system-destroying experiments from Atlantis is a good idea). Despite the constant sparring between the siblings, everything works perfectly, and they leave it running at low levels to see if anything goes wrong before ramping it up. Naturally, it doesn't take long before Zelenka is frantically radioing in to say that a foreign object has appeared in the midst of the containment field.

The foreign object turns out to be named Rod McKay - our Rodney's alternate universe counterpart! And gee, what a nice guy he is - he even has a leather jacket (he's just that cool)! It seems that the experiment, while successful on this side, ripped a hole in the fabric of spacetime which is threatening to swallow up alternate!Atlantis. Followed by the rest of the universe. Weir obligingly orders the experiment shut down, and Rod proceeds to charm everybody, to Rodney's growing consternation.

Suddenly, the experiment starts up again. It turns out just unplugging it didn't fix everything. The science team on the other side has a plan that will close the rift by destroying our universe. All three McKays (Rod, Rodney, and Jeannie) put their heads together and find a solution to save both universes. Unfortunately, this solution involves both sending Rod back (perhaps fatally) and severely depleting the ZPM. There's nothing else for it, though, and they send Rod on through. Just shutting down the bridge between the two universes uses up most of the ZPM's power...but McKay has to push it just a little farther to ensure that Rod survives to the other side, and the ZPM is wholly depleted. Weir decides not to fire McKay for leaving Atlantis completely defenseless, and Jeannie returns to Earth via the Daedalus.

Tropes:

 * The Ace: Alternate universe "Rod" McKay
 * Acting for Two
 * All the Myriad Ways: subverted; the techies have no qualms doing great damage to an alternate reality until they find out that life also exists in it (a chance that was considered astronomically small).
 * Alternate Universe
 * Aw, Look -- They Really Do Love Each Other
 * Brick Joke: Rodney recorded his message to his sister back in "Letters from Pegasus".
 * Department of Redundancy Department: The computer screen reads "ZPM module depleted" - which expands to "Zero Point Module module depleted"
 * Embarrassing First Name: McKay's first name turns out to be Meredith -- to everyone's amusement but his.
 * And perhaps the even more Embarrassing Nickname "Mer"
 * Girl of the Week: Sheppard may have had thoughts of treating Jeannie like this, but McKay shuts him down preemptively.
 * Hot Scientist: Jeannie
 * Hypocritical Humor: McKay warns Jeannie against Zelenka's ego.
 * Meaningful Echo: Early in the episode, Jeannie calls Rodney on never communicating, even for holidays: "Just two or three times a year? Are you happy? Are you okay? That would have been enough!" At the end, Rodney admits he's wrong (a very rare occasion), and as the two tearfully embrace, Rodney asks, "Are you happy? Are you okay?"
 * Nice Job Breaking It, Hero: This time, McKay nearly destroys the Universe - and not just this one.
 * Not to mention completely depleting the ZPM.
 * Pet the Dog: Afer McKay has spent the entire episode being completely overshadowed by not only his younger sister but his far pleasanter alternate universe self, the rest of the team admit at the very end that they found "Rod" increasingly creepy and annoying, and are happy with the McKay they've got.
 * Real Life Relative: McKay's sister Jeannie is played by Kate Hewlett, David Hewlett's real life sister.
 * Recycled Set: the house used for the exterior of Jeannie's house is the same one used for Samantha Carter on SG-1
 * We Want Our Jerk Back: Consensus is that an outgoing McKay is actually worse than an aloof McKay.