Normally a birth right; a child born of a "magick" bloodline is bestowed with magnificent powers, and is then raised and trained by an elite group under the direct jurisdiction of the queen, and the queen alone.

However, under very rare circumstances, the magick bloodline can (and has) run thin, and the number of knights can diminish drastically. In times such as these, nature takes matters into her own account, and bestows the magnificent abilities of a knight upon an outsider; forever changing their destiny.

Under the normal rules of nature, and the rigid rules laid down by the queen; this "natural selection" poses a problem. For starters, an individual born as a simple, mortal creature... the shock and overwhelming change that comes witht he sudden acquisition of these powers is capable of killing the host creature on the spot. (On that note, if it doesn't kill them immediately, it will certainly drive them insane, and render them completely senile at a rather rapid pace.)

Secondly; under the assumption that the acquisition of powers went smoothly, and did not kill or mentally damage the host creature, the newly powered individual has not gone through the nearly life long training (up until that point) on how the powers are supposed to function. The queen's team could salvage the individual, and train them yet; assuming that they even knew that he/she existed in the world at any given time.

Under such common circumstances (for such an uncommon occurrence); there wanders an individual with powers beyond their comprehension, and a mind that, more often than not, can be easily swayed over to the dark side. Or, simply a renegade knight who knows no rule to follow.