[Village Idiot]

Originally Posted by gammaoh

Spoiler:

I do think that Archer wouldn't have been able to kill Shirou in UBW even if he wanted to

Why? Because the simple fact that Archer exists means that he had already lost the fight. Because winning it would mean some kind of a non-existence, which is intelligently mentionned here as a time paradox.

If you could travel back to the past. And kill yourself, would you succeed?

The fact that you managed to kill yourself means you've lived up to the age during which you decided the killing. But if you've managed to do the killing, you wouldn't have lived up to that point and decided to do it. Hence the fact that you can't have killed yourself...

Did anyone get what I meant?

Spoiler for UBW spoilers:

In UBW, Archer could have killed Shirou and he would still have remained a Heroic Spirit, because the Shirou in UBW would not have led to the creation of Archer, they became different people.

The Shirou that would led to the creation of Archer is either from the Fate scenerio, or another alternate timeline.