Now this is the normal process for most Dragons, but not for a Wish Dragon. A Wish Dragon also requires the Blue Flames of Magic and a Wish for their unique egg to hatch.
For the Flames of Magic to occur, the Wish Dragon must be willing to sacrifice it's most important possession. Some might call it the ultimate sacrifice.
When this great sacrifice happens powerful magic is created. That magic floats above the little egg awaiting a wish to release it.
Now you may be asking as to how this applies to Dewin's Spite? She was born when the Dragon that moved the village to the Realm of Wymsy realized that he screwed up. When the Dragon sat on the mountain he created the situation that caused the mountain top to fall which would crush the people of the village. As he was a Dragon that lived to "harm none", he sacrificed his life and with his last breathe, made his final wish saving the village and it's people. With this act, he was turned into a blue flame, the Flames of Magic. This sacrifice and wish then combined - and as another Wish Dragon was hatched, so too was a Spite created.