It's not a leech because it doesn't affect the host negatively, it's more like clothes – a perfect dressing, a low-maintenance host.

The conditions have to be just right and then it springs up overnight, as if from nowhere. It's kind of magical...like birth and all creation, something appears where before there was nothing. Imagine, all of the factors that have to be just exactly right for something to appear, so unexpected if you're not paying attention.