Two people have so far told me that in the roo verse I need to explore why John prefers Rodney over Cam, maybe even getting to the heart of what makes John want Rodney and what makes Rodney want John. I think the roo verse really brings this home because John has every reason to want Cameron instead of Rodney, but doesn't in the end.*
The only problem is that when I think about it, I have no idea why John and Rodney are "meant to be." I am afraid I may have been so taken in by fandom that I just follow others without question when others are actually very, very wrong.
Check out the reasons why I can think J/R are shipped and they're all because someone has a psychological issue, not because of the characters:
1. They have great onscreen chemistry. Very true, but in real life would they even be friends? They need to get along professionally, and care about saving each others lives, but Rodney is really annoying a lot of the time and John is so stubborn and standoffish that I can't see how it would actually work. Some of the things John says to Rodney are very mean spirited, and Rodney is a genuine asshole a lot of the time. They have chemistry because DH cannot possible be as annoying as Rodney McKay in real life and JF seems to like playing himself whenever he thinks he can get away with it, so their real life good relationship comes across.
I think a large problem is that TPTB make Rodney a Maury Tsu, and having John like him is part of their fantasy of having the superhero jock suddenly turn out to be a secret geek and like them, which leads to Rodney being very protective of his friendship with John, giving rise to fic.
2. Rodney is the biggest Mary Sue in fanfic. I just finished reading a couple of the really bad woobie-rodney who needs John the knight in shining armor to save him fics and was pretty disgusted with myself for reading them. I think a lot of people in fandom sympathize with Rodney because either like TPTB they sympathize with his socially-isolated geek or because they like to imagine superhero John coming to their rescue ala harlequin romance novel. That's all well and good and it certainly helps service a guilty pleasure, but it's not authentic. It doesn't provide actual motivate for the characters if they were real people.
Which is why nobody ever questions Rodney wanting John (his hero worship is cannon, after all), but as authors we're always searching for reasons for John to like Rodney. However, I think I've come up with some admittedly jaded reasons why John and Rodney might want each other if they were real people and I don't think anyone in fandom will like them:
1. Rodney likes John because Rodney is the stereotypical maladjusted geek and thus incredibly superficial. Having has little to no interaction with women, he generally views them as objects ("why don't I get kidnapped by hot aliens?"). Katie Brown was 100% wrong for him but he almost married her anyhow based on only two criterion: hot and interested (yes, she may have been smart but he certainly never respected her intelligence). Rodney may want John because everyone wants John, but I think he really would only want John for the same two reasons he wanted Katie: hot and willing to put up with him. Those are terrible reasons to want someone, but I think they are probably the most authentic to his character, because he's an asshole, no matter we want to sympathize with him, and by making him into a Mary Sue we're basically telling TPTB that yes, they can get the dream girl they in no way deserve because we love McKay even though he is an ass.
Of course everyone gets all pissed at Keller for "trying to change" Rodney, but between John and Keller, Keller is totally the better catch because she's not super dysfunctional and she can actually make Rodney a better person. Why is it such an offense to want to be with someone who sees something better in you? The ridiculous fannon idea that John and Rodney are better off being dysfunctional together than part of healthy relationships completely baffles me, even though I am a Keller-hater for totally unrelated reasons.
2. John likes Rodney because John is incredibly fucked up. John is terribly awkward but has been blessed with good looks that get him by. He is anti-social and very emotionally unhealthy. Rodney, for all his bluster, is not threatening to John. Rodney is even more awkward so John will never be made to feel uncomfortable and Rodney hero worships him so much that he can hang up on him in the middle of a conversation and Rodney will still be grateful to see him. John also has a savior complex, and Rodney needs to be saved a lot of the time. I empathize much more with John than Rodney when I write, which I guess makes me fucked up as well, and I have dated guys like Rodney and I know exactly why I do it even when I can say very John-like mean spirited things to them - their gratitude for being with me is a power trip, and the fact that I know I could do better, that I'm doing THEM a favor by being with them means I can always keep them at arms length, because I'll always be in control of the relationship that way.
In other words, I'm a McShep shipper until the end, but I don't know why anymore, maybe because it's fiction and in fiction when people have fucked-up co-dependent relationships nobody gets hurt. Perhaps this is why in several of my fics (some not yet posted) John and Rodney's relationship kind of destroys the world.
Actually, if I had to pick who would make the BEST partners for John and Rodney I would definitely ship Rodney/Teyla and John/Cam, but they're not loud and dynamic and as explosive and fun to write.
*I have a few of my own reasons for wanting to give roo Rodney and John a chance: I don't believe that the genetic parent of a child should neccessarily be in that child's life as a givein; the societal rules of the rooverse are very different than ours and I think I have a good way to showcase that; and because I started out writing a J/R fic and I intend to follow through.