So originally he was a scary blood thirsty monster (I drew those in my childhood too. ) and then you started drawing him with Sweetpea. It's interesting to see the original darker side to the character. ^^
Here's my thing about these characters: were they ever used for anything? I mean, they look good and stuff, but if a character doesn't have a backstory and interactions, they are scarcely a character at all, and all I ever really see is quick sketches and at the most two characters interacting at one time. I think it would be much cooler to see them in an extended storyline than what you've done so far.
My friend has a huge problem with this, and my response is always the same:
Just do it. It doesn't matter if its crap, because then you can get criticism and change it and whatnot, but if it doesn't exist, its not going to exist. And the greater the gap in production, the likelier it gets that it never happens.
Strike while the iron is hot! Ponies are fun and all, but original work can be so much more fulfilling personally.