I've never understood this. Dragonborn has always been the one destined to eventually confront and defeat Alduin, right? If so then why does he save the Dragonborn's life at Helgen?

Been a while since I progess very far in the MQ, but did Alduin know the Dovakiin was present at the time? Was the PC even Dovakiin at the time?

I don't think it was intentional. He either didn't even know the Dragonborn was there, or he was trying to kill the Dragonborn without realizing he would've been better off letting the executioner finish his job.

It's a time honored tradition for Villians to toy with their prey in games, books and film. Alduin wasn't trying to save you, he's just playing with his food, and bungled and you got away. It would be a really short game if they cut your head off in the opening minute of the game.

I don't think Alduin knew. Mirmulnir certainly didn't know either, up until he felt his soul being stripped away.

I always figured it was random chance or perhaps intervention by someone or something else that saved the Dragonborn's life. Seems as if it was known who the Dragonborn was that at one point or another multiple dragons would have attacked to make sure the Dragonborn died.

Don't forget, Ulfric Stormcloack was also there. Alduin's attack disrupted his execution as well and planted the plot seed for a Stormcloack/Alduin conspiracy.

Alduin didn't know. He'd just re-emerged, and was angry as all get out. Helgen just had the misfortune of being the first thing he found.

So he was there to save Ulfric? Why would an all mighty "World Eater" need little Ulfric?

to allow the Civil War to continue

"the elder scrolls told of their return, their defeat was merely a delay. for the time after Oblivion Opened, https://www.youtube.com/watch?v=hGMOMkACtn4"

The more Nords dying the more souls he has to eat in Sovngarde.

Alduin was tossed out of time for thousands of years, pretty sure he has no idea who Ulfric is.

It seems to me that upon Alduins return he senses the Dovahkiin nearby so attempts to destroy him before he can become a fully realized dragonborn. I don't think he can pinpoint which mortal he is, only feel his soul or something...notice how he pauses while staring at the group, as if he's trying to determine which one is dragonborn. Alduin seems to pop in at several points we're running thru, again getting a general feel for our location. He tries to kill us but inadvertently saves us before moving on to resurrect his fallen dragons.

So then, he was there to kill you? He just didn't know who the Dragonborn was, only that you were in that area? Ironic considering your state of affairs at that exact time! It's also ultra unlucky for him. If only he was 30 seconds late, or better still hadn't bothered to attack at all! In other words he caused his own downfall by trying to assassinate you?

In other words trying to make the intro more flashy.

Yes, in terms of game production, that was the best way to introduce the villain and the threat he was to the world. But in terms of in world logic, it didn't make sense.

He didn't save my first Dovahkiin. He fried her to a crisp.

Poor little Dragonbornette...

Unfortunately most of the time gameplay will surpass in wold logic.

You could say it was just coincidence after coincidence, Alduin just happened to pop by near Helgen.

Alduin returned and started it by burning a random town. He didn't knew about the Dragonborn and was never trying to interfere in our little decapitation issue with the Imperial authorities. But yet he did interfere and saved Dovahkiin and that is what was supposed to happen when we have a small factor called "destiny" messing around.

There is a possibility that Alduin could have some sort of ESP for sensing Dragonborn's presence. Being a mythological creature I guess a lot of thing like this are possible. It's certainly not beyond all credibility.

I believe Haggar is right. I recall reading somewhere (UESP, maybe?) that if you take too long to get into the Keep, Alduin eventually starts targeting you more directly. No idea if that's true since I've never hung around, but assuming that it is it ties in with that whole idea of Alduin sensing the Dragonborn, but not being able to pinpoint them immediately amidst the crowd. Maybe he thought it was the Executioner, since that's the first guy he attacks

I just got killed by Alduin in the Helgen intro . Was very odd, I was just stood around watching him (I normally just sprint all the way through) and he landed in front of me and shouted. The view switched to 3rd person and I flew into some rocks and looked dead, but I got up and it returned to 1st person. Then he landed again and bit me and I died for real. I didn't have subtitles on so wasn't sure exactly but it did sound like he was talking to me, i.e. full sentences not just shouts. (Edit: this is more relevant now with the post above!)

To make this point slightly relevant I think he does know who you are, his mad dragon skills are maybe just a little rusty. If you think about it, he smashes into the tower you have escaped into and blasts fire at you, lands right in front of you and the little kid and blasts fire, the whole 'keep close to the wall' moment and the two cave ins once inside the keep. He's after you alright.