The coming of the rains is what draws your attention to the hordes swarming through the trees and towards the Ark. From the ground, you allow your eyes to trace the paths that the well of Eden has taken, and spy the floodgates waiting to erupt, a slumbering beast awoken only now, years after the seed was planted. It had been miraculous then; your brothers, long since jaded by the passage of time and the silence of their Creator, found new faith. So did you, in the worn human they called Noah. And so you cast your lot in with him and his family, and you helped construct the Creator's Ark, and now... this.
Cain's brood swarm through the trees, warlike and savage. With your rough stone bodies, you and your brethren mass around Noah, offering them safety against the mob. Blows land upon you, but your heart, dampened by the crude matter that is your vessel, feels nothing. When you were an angel, you had felt the pain of the Exodus so deeply that it drove you to the newly-formed Earth; here, as you mark your last stand, surrounded by kin, you are insulated from the pain through layers and layers of rock, of lumped granite and scabrous coal, of the filaments of your grace weaving through your flesh and affording you a measure of warmth against the chill of the flood.
As they hammer at you, you drive them back with lengths of chain and force. An odd sentiment touches you.
You do not want to leave.
Perhaps in the early centuries of your exile, you might have sought freedom. You saw others commit the unforgivable sin when the Creator refused to answer: the murder of the self. But as the years grew thinner, you felt love for the hairless apes that abounded, casting their light against the darkness of a planet uncolonized, and in time, you even grew to care for them as though they were your own. Emotion, in its purest form, had been your first state of existence, before you Fell. Somewhere along the way, you lost it. Here, you feel it again; more brilliant, more magnificent than any star, any flare of golden sun.
Thus, you stay behind. You, the last of the Watchers, stand firmly to bear witness - each brother's death is exultant, ebullient, and you can feel their joy as they take to the heavens to be reunited with their maker - while all around you, earth crumbles and men are swept away by the careless waves. Noah, your dear companion, watches from the doorway, held down and blinded by the storm. In your heart, you hope that he does not see you as you draw your life to a close, and yet, you also hope that he will witness your ascension. Such strange thoughts run through you, bordering on heresy. When you deign to speak, your voice comes out in its usual rough baritone, a mournful sound, but your eyes are shining.
"Goodbye, Noah."
Without a trace of hesitation, you tear apart the rocks holding your form together. From your chest, your soul erupts, scattering those closest to the Ark and setting them aflame. Your own heat scorches you, enthralling you after millennia of captivity. Howling, you reach for the skies, and maybe you do not notice the man Noah down below, still gazing at your departure on the rain-drenched earth, shaping your name Og - one Watcher lonelier.