It is done. Corypheus is defeated. For a night, you celebrate and bask in the knowledge that you have triumphed, despite the painful ache of the one missing from your side.
Then, little by little, you become isolated. Solas left before the victory celebration, of course, but he's not the only one who departs. Thom is sent to the Wardens, according to your own judgment. The Iron Bull, bereft of his Chargers, returns to the Qun. Cole simply disappears one day, never to return. Cassandra departs to reform the Order of the Seekers, just as planned. Vivienne ascends to become Divine Victoria, and her first act is to declare the Inquisition a heretical movement. Dorian departs for Minrathous, hoping to find something to salvage in the land he loves so much. Sera shrugs and returns to Val Royeaux, mumbling about how the Inquisitor doesn't know how to see the little people anymore. Cullen returns to Honnleath and hangs up his sword, and Josephine accepts the invitation from Val Royeaux to be an Advisor to the Crown. Even Leliana spends more and more time away from Skyhold until, one day, a note arrives with only the outline of the Grey Warden symbol with a raven resting upon it.
So you sit upon your throne, watching as fewer and fewer people return each day. Holes go untended, walls begin to fall again, and all you can do is wait as Skyhold rots around you.
And what of you? You are too busy watching the rot of your own body. The green grows slowly, claiming your hand, then your forearm, until one day you awake and feel nothing but pain where once your arm was. You try cutting it off, but the green simply flows into place over your shoulder, and you feel the agony of the magic thrumming with every heart beat.
Dragging yourself to your throne, you collapse upon it, weeping in agony and fear, as the green begins to spread over your chest. The light around you rises and falls, slowly at first, but then with increasing frequency. It grows cold, then warm, then cold again, but you no longer recall what that means. The green spreads, consuming your body and your soul, changing you along the way, but somehow you can still see, can still feel the pain, and still remember that once you were the Inquisitor.
And then, one day, he returns to his oldest home. Stepping over the debris, he comes to a halt in front of the remnants of the throne and retrieves you from where you sit. Holding the new Orb between his hands, he smiles and plants a soft kiss upon it. "Ar lath ma, vhenan," he says in a hushed voice.
And then he departs, with you held close. After all, his task is not yet done.