So i made a thread some time ago about what trully meaned the return of the Dragonborn.Anyway almost all the replies where off:topic...I'm also adding other things.
Anyway let's get to the point.My conclusion of this theory came'd from speculation of other members.Looks like the true history behind of the Dragonborn can be compared to he main plot of Infamous,reply form "Nago"(and thanks http://www.gamesas.com/user/706292-distance-and-hope/ for the plot reference):
""sems that they have knowledge about the future but then it turns odd that they were surprised by the return of the Dragons. All this makes me to believe that everything is connected to the divine of time. This divine's one aspect, Akatosh was the protector of the Empire and his acts stopped the Oblivion Crisis. Well then his Nordic aspect Alduin returns to world and brings the other dragons with him. (Alduin is probably the reason why return of dragons was hidden by Aldmeri Dominion.)But there has been nothing about the elven aspect Auri-El. I think the reason is that the Dominion actually works with Auri-El and I believe his role is to be the protector of the Dominion as the Akatosh is the protector of Empire. Auri-El may be the key why Dominions timing is so perfect. Does this make any sense to you?"
This probaly means that the true reason of Alduin coming to the world right now with all of "it's power" could be just because to make Dovakhiin stronger.With alduin ressurecting the Dragons dovakhin could just eat their souls and become stronger.This also could explain."

Spoiler

Alduin weakness at Sovgard

Spoiler

Also with the defeat of Alduin,the dragons needed no longer to obey him.And since Dovakhiin is a mortal born with soul and power of dragons he could summon the dragons to aid him in the battle agaisn't the Thalmor

Spoiler

Also with the defeat of Alduin,the dragons needed no longer to obey him.

And since Dovakhiin is a mortal born with soul and power of dragons he could summon the dragons to aid him in the battle agaisn't the Thalmor.

Spoiler

Let's not forget that Paarthunax is the new ruler of teh Dragon kind,so he would obvilious aid Dovakhiin

Let's not forget,if that is true.Alduin will return stronger than ever if Akatosh is aiding him...
If my theory is true,this means that the "True purpose of the World Eater" is just too literal.But in fact,something like 2012 profecy that says:
"The world will not end in 2012,homever will dramastcly change." This can beeing seen by mortals as the end of the world.Since "The world they knew'd is over."
In fact,the live of the people on the time of the current " TES game',would be extremely affected if Dovakhiin defeated the Thalmor,retaked the Thalmor's possed lands and defeated the Falmer.
This is why my theory looks the Plot of "Infamous".Because the true purpose of Alduin/Akatosh was to make Dovakhiin strong enough to defeat the true great enemy.

Even with the spolier tags... this goes way too far for this forum.

I Agree...This is why i tried to minimalize the spoilers.But serilious...it's more than obvious, even some months ago that you would defeat Alduin

there's a "Cheats, Hints and Spoliers" sub-forum for this kind of discussion.

So plz i ask for a moderator move the topic too there....

Yeah, I could see it.

Wait, isn't it that Dragonborn will come whenever Alduin comes?

Alduin does not come because a Dragonborn is born, it's the other way around

I believe statement number 1. Unsure though.

Cheers

You make a valid point.

Alduin wants skyrim to be ruled by dragons.

Cheers

Hmm... I didn't think of that. But then again, Alduin only comes when the time comes to destroy the world. Besides, if the intention is to empower the Dovahkiin and help fight off Thalmor, Alduin need not to die, as there is no guarantee that Dovahkiin or the other dovah will do as he intended

Alduin didn't knew that his goal was to emporer Dovakhiin But only Akatosh knew If he knew'd he would just stoping of ressurecting Dragons and hide.Because you guys know...with more shouts much more stronger a Dragonborn is.