...wouldn't you absorb every single dragon soul that he's devoured? My reasoning goes something like this:

A Dragonborn is uniquely able to halt a dragon's cycle of physical death and resurrection by devouring the essence of its being (its soul). Now, when a dragon's soul is devoured, the dragonborn also gains the accumulated knowledge of the dragon; it is this knowledge that lets the player "unlock" new words to Shouts. Also, since the altar encountered in the "Horn of Jurgen WIndcaller" quest is able to confer a soul to the player, it seems as though souls do not have to be consumed from freshly-slain dragons but can also be obtained from other sources. Additionally, a dragonborn is, to my understanding, the soul of a dragon stuffed into the body of a mortal. So it stands to reason that, if a dragonborn were to slay another dragonborn, the killer would receive the knowledge of the victim... including the knowledge of every single dragon that the victim killed over their lifetime. Which, in the First Dragonborn's case, seems to be a lot.

So, for everyone complaining about having nothing to do with the 100+ souls you've collected in your journeys through pre-DB Skyrim... your problems may only grow larger...

dragon soul overload. dovahkiin.exe has stopped functioning.

But i don't want to kill him he has the same cause as I do. Dragon genocide. I wanna team up with the fallen dova.

not gonna happen
even if it can be explained with logic from the lore
beth isnt gonna make it where your soul count goes up by 300 after you kill him
itd just be stupid

the seconds jumps from the shades, hitting godzilla with a bat grenade.

THERE CAN BE ONLY ONE

Something tells me he's not exactly cooperative at this point, but who knows?

Who knows...
Maybe we'll get a cop-out like with Alduin- Not really kill him, just displace him. Or capture his soul or something in another something. Somethingception.

It'd be amazing to have him as a follower...

Maybe there will be an option to marry him?

I'll devour his soul

He's your senior... You'd be HIS follower.

Maybe all the dragon souls he ate will be freed once he dies. If the dovakhin are 'sponges' trapping the souls, breaking the vessel will release everything at once, a process too violent and fast to allow another dovakhin to catch every soul once trapped.

I hope once we do the cooldown on our shouts goes way down.

Would be cool if we absorb his soul and gain the shout "Do" "Vah" "Kiin" that calls his spirit.

Maybe when he dies, he farts out all the dragon essence into a shout. Shouting FUS RO DAH! with his behind so hard the world of Nirn ceases to exist?

On a serious note I like your logic. But I doubt it will happen

I second this notion.

I think he can only be killed via decapitation (or maybe his heart getting ripped out anyone?),

Because when they find all the shouts. They won't wait for Dragon Area/Word Walls to Get the Soul. They will Download Dragonborn. and get all those Souls that the Dragonborn 1 Has

And every soul that doesn't get caught resurrects the dragon. Hundreds of dragons come back to life, all of them pissed off and looking for revenge on the Dragonborn you just killed.

...or any other Dovakhin that happens to cross their path Sweet!

Would you like to send an error report?

But.... why do we have to kill him? Assuming that is what happens. As long as he leaves me to my elk hunting and occasional stroll through the wilderness, he can devour all the dragons he wants - saves me from slaying dragons for a while

He might have a couple of unique dragon shouts that we absorb from him, but they won't unlock all of the vanilla Skyrim ones.

And I really hope he's not automatically an enemy. More than likely, he will be though.

hmm... never thought of that, absorbing all of his collected souls....another dragonborn.

sorry i cant help but go back to the mantling concept. it makes sense to me.
this could be another way to reach divinity. to fill the void of the absent god.

Well that could be nice for a change, if they managed to make it work properly. Or maybe by defeating him you can somehow subdue him to follow you, although I think that's highly unlikely...

Chances are he has to die.