Like Meg, Castiel is now drifting. He goes from town to town, virtually without a cause until he'll eventually find one to serve.
Meg spent her years on earth borrowing name after name, using them and shedding them as easily as one changed their clothes. She became that person, wholly, until it was time to move on. Time to say goodbye to that life and that name.
So, with nowhere to go, no cause to serve, Castiel shows what he has learned from her and becomes Clarence. He lives and breathes as this new person, this name she has given him. Coined after an angel trying desperately to gain his wings.
But that way lies danger and more heartbreak, turn after turn. Perhaps finding his wings again was a terrible purpose. Just as Lucifer was hers. He'll need another.
So he becomes Steve.
Once, he was an angel of the Lord.
"And now I'm a sales associate."
Is it ideal? Certainly not. It's humiliating - just as being a fugitive from Hell was for her - but at the same time, perhaps it's the start of something. Something bigger than both of them.
Something once as unfathomable as a demon laying down her life for an angel.
And maybe she'll be back, with a new name.
Meg may be gone, but only the chapter is over. Her story is just beginning.
And so is his.
They'll meet again. Maybe another ring of fire, maybe another abandoned factory, hospital room, or threadbare couch.
Maybe next time he'll be the demon and she the angel.
Fate saw what they made of each other, how loyalties shattered when they shared a room, shared a kiss.
Just as the planets in orbit, it may take years, it may take lifetimes, but their paths will cross again. Maybe there'll be another apocalypse, maybe they'll be running from the same thing. Or maybe he'll simply see her one day across the aisle, buying groceries. She'll have a new meatsuit, a new name - maybe he will too - but he'll know it's her and she'll know it's him.
Those with no name of their own have a habit of finding each other, regardless of time or reason.