I thought about this quite a bit when I was writing about Black and White, and when I reviewed the Victini movie. In both the games and the movie, Reshiram and Zekrom are basically interchangeable, as are their values. This is necessary so that the same story can be told whichever one N partners with, and is made possible largely because the writers seem to have a very loose interpretation of what ‘truth’ is. I think this is the real problem, rather than anything in their physical designs; both Reshiram’s ‘truth’ and Zekrom’s ‘ideals’ basically boil down to “the way you believe in your heart the world should be,” so there’s nothing to distinguish them conceptually. Zekrom stands for ideals and Reshiram stands for truth, but ultimately both of them admire and reward the same things in their human partners: the desire for change, and the will to pursue it. Honestly, I don’t think they’re forces of ‘truth’ and ‘ideals’ at all; I think they personify conflict itself in a way so abstract and primal that our pathetic little human minds just give up and start arbitrarily assigning them to pairs of opposites like light and dark, male and female, or passion and serenity, in an effort to explain their nature in terms we can understand. Since playing the sequels I’ve actually come to think that the fuzziness of their boundaries is intentional; you can see this, for instance, when you meet Drayden in the sequels and he talks about how, in spite of their long-standing and bitter opposition, Reshiram and Zekrom aren’t even all that different, and don’t really need to be enemies at all. I think the fact that you have difficulty remembering which is which is sort of the point; the whole thing, I suspect, is supposed to be an allegory for the wastefulness of conflict.
All that said, I don’t really like the way Reshiram and Zekrom were handled. If I had been running Black and White, I probably would have demanded significantly more divergence between the two games in the way the story unfolded, to give room for Reshiram and Zekrom to look for and cultivate different qualities in their chosen heroes – Reshiram respects intelligence, discipline, pragmatism and an analytical worldview, while Zekrom respects confidence, passion, determination and an idealistic worldview. N could actually fit either of these – he can earn Zekrom’s trust through his desire to change the world for the better and his dedication to his cause, while he can command Reshiram’s respect through his undeniable brilliance and his ability to view the world with mathematical objectivity. I think I would probably work this by playing up different aspects of N’s personality on the different games, to make it more obvious how he fits each dragon. Then, starting from the point when the player obtains the Light Stone or Dark Stone (which I might put earlier in the game), Reshiram/Zekrom will begin sending the player visions or dreams that require difficult moral choices (“who do you save and why?”-type dilemmas with no ‘right’ option, both choices leading to a different explanation from the dragon about why you suck), basically with the intention of moulding you into a hero who suits their preferences.