Yeah... That is indeed Tails, but in this time, he went by a different name...

You see, after playing around with some off-the-wall theories on why the kid has two tails, I concluded that he was a demon.. and his true name: Nachiah.

He was the keepr of the chaos (an idea adopted from a fan-fic I read), meaning he was the guardian of the chaos emeralds. When the whole mess with Chaos went down eons ago, he almost lost his life, so he sealed himself within the hidden palace so he could regain his strength. It took quite a long time to be released, but he ended up as a child again, who is the Tails we all know and love. The other name, Miles, came from the woman that found him and raised him until her death. The rest, is history.