I think you'll be a supporting character to the Dovahkiin. All of this "you're the chosen one to lead us to safety, oh macho man supreme leader commander lord of magnificence!" stuff just gets old.
They did that in Oblivion already, and it really did not work out so well. I'd take being the hero over being the hero's sidekick who still has to do all the work any day, unless for some reason being the hero just isn't possible.
Just because something has been done before doesn't mean it gets old, it only gets over when it's been done so many times that it starts to get boring, and being the hero is by nature NOT boring because one usually assumes that all the most interesting things are happening to the hero, and if the person who gets to have the most interesting adventures is someone other than the main character, then in most cases, there's really no reason why the main character shouldn't be that person instead, since I'd surely rather be playing as that person.
Now the notion that just because it's been done before means that it's now suddenly a bad idea for the protagonist to be the hero, on the other hand, is getting old.
You're right, because that is the ONLY way you can pull off a supporting role.
If you have another idea, I'm sure we're all willing to hear it. Admitably, it's not the only approach you can pull this off in SOME mediums, I mean, books can get away with having the story told from the perspective of a different character from the one who is actually most central to it, but books differ from video games in the fact that they're not interactive. In books, as long as you get to see (Okay, read about, but you get the idea.) the important things, it won't ruin the work if they're not necessarily done by the person whose perspective the story is told from. But in games, you have pretty much no choice but to have the player character do the important work, because it would be pretty boring to sit around and watch SOMEONE ELSE do quests. Thus, by nature, if you try to have the player be a supporting character, you'll get a situation like Oblivion where you're actually the one doing all the work, but someone else get's the biggest honor. The only real way to avoid this would be if the player controlled more than one character over the course of the game, thus, you can have multiple people having the important adventures, since each of them is controlled by the player, but that wouldn't work for a game like the Elder Scrolls.
In Oblivion, you really felt like you were the super-duper-kick-ass-master-of-the-universe until the VERY end, where you were suddenly the supporting character. I mean, you did everything BUT light the fires.
And that's part of why I found the conclusion to the main quest rather unsatisfactory. Really, because I did all the difficult work, yet in the end, Martin is the one who gets the honors, I just get a crappy suit of armor. I have other problems with it as well, but this is the one relevant to this subject.