When Spike and the CMC get in a bind, his true nature is revealed to Ponyville and all of Equestria.

Spoiler Alert: Spike is often overlooked. This isn't one of those times!
NOTE: This story is not going to be canon-compatible for very long. But Spike fans like me would most likely wish it would be.
Awesome artwork by bobthelurker (http://bobthelurker.deviantart.com/art/Spike-My-Card-Vector-345430619)