Quote Originally Posted by Silverraptor View Post
I've never seen that happen. Do you have a video clip of that?
The wiki confirms that he will attack you for real if you stay outside too long. But nothing about taunting or recognising you.

Personally, I think there's a lot of overthinking going on here.

Alduin emerges from the time wound at the Throat. Maybe he sees Paarthunax there and they exchange insults, maybe not - makes no real difference either way. Then he flaps off to look over his domain, and as luck would have it, he chances first on Helgen. He flies down and notices that instead of abasing themselves before him, the humans are actually showing every sign of readying weapons - so he decides to show them the error of their ways.

At some stage he realises that the humans clearly haven't seen a dragon in a long time, and deduces that his followers are lying under these huge circular mounds that dot the landscape, conveniently obvious to aerial reconnaissance. Then he sets out to raise them. But even for him, raising a dead dragon takes a lot of effort, which is why it takes him so long and he flaps away after each one.

Everything else comes down to timing. Why did Alduin appear exactly when he did? Meh, prophecy. The gods do that sort of thing all the time. (As evidenced by... Well, the whole of the rest of the game, really.) Why were Delphine and Farengar apparently already researching dragons? Coincidence. (It's clear from the early game dialogue that no other living dragons have been seen in living memory.) Also keep in mind the constraints of writing an open world game, where the player might head directly to Whiterun, but it's also perfectly possible they might not make it there for weeks - the dialogue has to be sufficiently vague that it makes some kind of sense either way.

And that's all it is.