"...Dark Pegasus is a terrible creature. No regard for anyone or anything."
Little is known about his personality, although his appearance in the strip so far has shown him to be prone to be somewhat impatient and fond of gloating. According to his official cast page, Impatience is something of a weakness, given that as a demon, he is quite capable of outliving most of his opponents (typically Beings), yet somehow he can never quite resist a complex plan to bring about their demise. He is also determined to do things 'the classic way' regardless of the risks.
Little is known about his past. However it is known that he has attempted to usurp the realm of Queen Hollyann on at least three occasions with the intent of resurrecting his dark master. On all three occasions he was defeated by Daniel Ti'Fiona, resulting in his death on two occasions.
It turns out that Dark Pegasus was the Demon responsible for the creation of the Undead race, approximately 30 years prior to the strip's current timeline. Since then he has tried to undo the mistake, slaying the undead when and where he can, though in his defence it seems that he has been molested by several groups of undead who wish their creator to join them, either out of vengeance, or as their leader.
An interesting note about this was posted by Amber in this thread:
Ironically enough, the children not being Undead was a deliberate action on Dark Pegasus' part. He, as well as a couple others he worked with, found the idea of using children and infants in his Undead army to be a disgusting idea and so put the parameters of the spell to not affect them. DP didn't have ideals of making an Undead world, he was more interested in an easily recycled super-army he could use however he wished.
Unfortunately several of the cults now have an ideal of making an Undead world. Which is partially why they are also so eager to catch up to DP. Dark Pegasus is, more or less, the master of this particular spellcraft. While there have been lesser forms of creating an Undead servant, DP perfected it and figured out what made it work to the point he was able to branch off and do some new things altogether.
Dark Pegasus does not appear to be evil for the sake of being evil, so much as driven and somewhat less than picky about how he achieves his goals.
As Amber put it:
The thing to try to remember with DP is that he doesn't particularly strive to be a villain or evil. He doesn't care for wasteful carnage or pointless acts of violence, and views those that engage in them as childish and lacking a true vision. In many ways he will often put civility as a priority. It is just that DP has goals, and he is more than willing to do things that are not "good" to achieve them. He doesn't really revel in acts of evil moreso than he sees them as an unfortunate necessity.
- Dark Pegasus created a number of undead servants known as the Death Knights, supposedly one of the only undead races which lacks free will.
- Like most demons, Pegasus has the ability to harden his skin and hooves. The hooves in particular can vary from soft, thus allowing him to manipulate objects, to razor-sharp - which dealt Dan a near-fatal wound in strip #157.
- Dark Pegasus can see into the infrared spectrum.
- He has the ability to vary the size of his wings, making them larger or smaller as he sees fit.
- According to Hannah, Dark Pegasus is renowned for his loathing of Undead. His legion of servants, the Death Knights, are powered by the souls of Undead.
- Amber has an irrational fear of horses, this may be why a number of evil creatures in DMFA are equine.