My guess is that the process of coping with seeing a death changes something in the way your mind processes, and that change is what makes it possible to see them.
Can Muggles see Thestrals?
Possibly, though I'd guess they rarely run into them.
Why can't Harry see the Thestrals at the end of GoF? There's a scene where they all see the "horseless carriages".
See above answer about processing the death - I don't think Harry had gone through enough coping with Cedric's death - it was too recent, and the change wasn't complete yet.
Why can't Harry see the Thestrals from the very beginning?
He probably didn't actually see his mother die. For example, she might have been holding him and his eyes could have been shielded. For another, he might have been too young to understand her death (he was definitely too young to consciously remember it) and therefore to deal with it in a way that would change his brain to be able to understand thestrals.
How does a Thestral know where to go when you give it a London street address, like Harry does?
Thestral magic - inherent, like a phoenix rising from the ashes.
Why are their names always capitalized?
Real answer - Rowling is too damn fond of capitals.
no subject
My guess is that the process of coping with seeing a death changes something in the way your mind processes, and that change is what makes it possible to see them.
Can Muggles see Thestrals?
Possibly, though I'd guess they rarely run into them.
Why can't Harry see the Thestrals at the end of GoF? There's a scene where they all see the "horseless carriages".
See above answer about processing the death - I don't think Harry had gone through enough coping with Cedric's death - it was too recent, and the change wasn't complete yet.
Why can't Harry see the Thestrals from the very beginning?
He probably didn't actually see his mother die. For example, she might have been holding him and his eyes could have been shielded. For another, he might have been too young to understand her death (he was definitely too young to consciously remember it) and therefore to deal with it in a way that would change his brain to be able to understand thestrals.
How does a Thestral know where to go when you give it a London street address, like Harry does?
Thestral magic - inherent, like a phoenix rising from the ashes.
Why are their names always capitalized?
Real answer - Rowling is too damn fond of capitals.
Fake answer - well....er...*whistles innocently*