There is no such thing as Black and White, Good and Evil, Yin and Yang. The world only knows the various greys in-between.
Nearly every culture out there has some manifestation of the righteous and the treacherous. The cadejo is no different. Hailing from Central American folklore, the tales of the cadejo varies from country to country but they almost always come in two separate variations. The pure, helpful white dog, and the malevolent, evil black dog.
The white dog helps to guide lost travellers out of the woods and is the only force which can kill or harm it's evil brethren.
The black dog that which cannot be killed, prowls the streets at night, searching for its next victim. Once it chooses its prey, it stalks. Almost nothing can draw its attention from the hunt. Its raspy snarls and soft growls can be heard, usually a sign of the victim's impending doom. Your only chance of escaping its open maw is the intervention of the white cadejo.
You have never been focused on the technicalities of life. Nor have you agreed with many people's boxed-minded views on the concept of good and evil. Nothing in this world is inherently good or evil. You choose to live your life in the grey. This does not make you a bad person. Your life is how you choose to live it and the choices you make along the way. You simply won't allow for moral conflicts to interfere with a logical train of thought. It is this perspective on life which has attracted the cadejo to you. Just be wary of your guardian, it is nearly impossible to tell which one it is until you see it and by then
it's already too late.