Something I've noticed is that are plenty of stories in which one of the Mane 6, the Princesses, or even a Villain has been replaced by a human via soul swap. Of all the ones I read or seen, I never seen one in which a human takes the role of Twilight's #1 Assistant: Spike the Dragon.
(The story "Ten Years Gone" doesn't count since the human in question became a female look alike of Spike, as opposed to literally being him)
If someone knows of a story of this sort of scheme, it'd be awesome if he or she could direct me towards it.
If there actually isn't one at all, I will leave this up as a story suggestion should anyone take this concept into consideration. Anyone have thoughts on this matter?

4962681

There are a few, but there is no straight up story to my knowledge, just rather reincarnation stories.

One of the better ones is The Poisoned Barb's Tale, and its previous story that only covers pre-canon at Canterlot. It's a rule 63 story where everyone is the opposite gender (while the character is only familiar with the canon show of the original gender). She's also an adult, a mother actually, previous to arriving.

4962681 I'm in the same boat as you. I remember though, in the early days of the brony fandom and when I first found Fimfiction I read a story of someone who became spike. I don't remember anything about it aside from it being pretty funny. Unfortunately I never favorited and forgot the name. After spending some time searching I came to the conclusion that it was removed from the site. Hopefully if we bring this to the attention of the group a talented author could make a very good one, or at least a decent one. I know I would read it!

I know of two stories, but they're incomplete:
The "Spike" Incident
and
Spike, where Louis C.K. of all people, ends up in Spike's body.