I think the secret message is that everyone has two parts: a good side and a bad side. No matter which one we choose to reveal, we have both good and bad parts. They combine to make one person- and we ae slaves to our mind and what we choose to be.
I dunno maybe I read too much into it or somethin'. XD just taking a shot~
Ok, so gonna take a shot here..
So, the happy random and awesome Pinkie is comforting the sad one who has chains for some reasons, and she looks kinda mad and somebody wants to use her and she is protecting her?
Anyways, awesome drawing.<br / />