In every seraphim lies a slumbering dragon. Not a friendly welcoming dragon or a greedy lizard over a pile of gold. Curled deep down its malevolence echoes his deepest fears and selfish desires.
Home - he's comforted by the sweet murmurs of his family. When he first woke his dragon was naught but a small wyrmling inexperienced in what moved the newborn seraph's heart and mind. It lurked deep down - feeding off his words, thoughts, and deeds - remembering what words prompted which memories and feelings it truly desired. It finds it's vessel most intriguing: the mouth savors over corrupting such a pure soul.
Outside - the wyrmling spreads its wings - testing its talons on its boundaries. Each little contact with the taint makes it grow - like a plant, a weed, under the nurturing light of the sun. It rejoices whenever its vessel tests its light against the world's darkness - waiting for the star to fall.
It questions his choices. Tests his limits. Flourishes in conflict, doubt, and selfish yearning. Shrinks away from selflessness and love.
Change starts inwardly, twisting behaviors, then spreads outwardly into a sudden manifestation like a virus or weed outbreak. Warping the pure into a tainted weapon of malevolence.
The dark is generous, and it is patient. It is the dark that seeds cruelty into justice, that drips contempt into compassion, that poisons love with grains of doubt. The dark can be patient, because the slightest drop of rain will cause those seeds to sprout. The rain will come, and the seeds will sprout, for the dark is the soil in which they grow, and it is the clouds above them, and it waits behind the star that gives them light. The dark’s patience is infinite. Eventually, even stars burn out. (direct quote from RotS book)