Disclaimer: I do not, nor have I ever, owned The Chronicles of Narnia
When Aslan told her that she would never return to Narnia, she felt betrayed. (What have I done wrong?) When they return back to England – never home, because Narnia is home, and she can never go back there and so will never really be home – Susan decides to lock up Narnia in her heart forever.
She wears a mask of lipstick and nylons and pretty clothing, filled with bright smiles and coy looks and friends who giggle and laugh. There are all the reassurances that she is fine, just fine. She does not show anyone – not even Lucy or Edmund or Peter – how she misses Narnia. She does not show how she misses being Queen Susan the Gentle. She alone knows that here, in England, that Susan the Gentle and Peter the Magnificent and Lucy the Valiant and Edmund the Just do not exist.
They can't exist, you see. People would think them mad. And Susan has always been one to care for what others think…
And so she hides with her nylons and lipstick and clothing; she goes out and gives false hope to a steady stream of boys and men (but they cannot, do not compare to the kings and princes who once fought for the chance to carry her favor). She is not as lovely as she was in Narnia, but she is still someone almost-as-beautiful.
And so she dances with boys and men (but they are not like dances back home, and her heart aches for dances with the trees and fauns and sweet music of Narnia) and hides herself – hides her heart, for she has left them both in Narnia, how foolish of her – as Peter and Edmund and Lucy look on, angry and confused and sad. They are fooled by her mask (but that is half the purpose of the mask, after all).
And then it happens – that horrible, horrible train crash. And her mask of nylons and lipstick and pretty clothing disappears – for who does she have to pretend to now? She is allowed to cry, now. After all, her entire family is dead. She is all alone. Her heart is allowed to feel as though it has been broken into a thousand pieces.
And she goes to the Professor's house – left in his will to the Pevensie children, but she is the only of them left so she gets the whole house – and ends up curled up in the Wardrobe. She cries to Aslan why have you forgotten me?
And she runs away to America, just like that summer when Edmund and Lucy and Eustace went to Nar – no. She goes out and dances with boys and men (all the while wishing she could dance the wild dances of spring and summer with the trees and the fauns and in Nar– ).
One day a man asks her to dance and Susan finds she is almost captivated by his kind, sad eyes.
He too, has lost his home, Susan discovers.
"Would you rather hear the truth or a lie?" she asks him once.
"Tell me one of each" he says to her.
"I was a Queen, once. And I am a fool." she says, (but she is not quite sure which one of the two is the lie for she wakes up some days wondering whether Narnia ever existed at all).
She marries that kind eyed man six months later. She knows she cannot fully love him, and he cannot fully love her. The problem is that they have both lost their hearts to places they can never return to, so it doesn't hurt to know that they will never be in love. It is alright. She is happy enough with him, she supposes, for all that she still cries in the darkness, when she thinks he is finally asleep.
They have three beautiful children, two boys and a girl (and her husband suggests, tentatively, that they name them after Susan's siblings, but Susan refuses him with a cold look and gives them all names that remind her of nothing. Susan does not want to look at them without seeing the disappointed looks of Lucy and Edmund and Peter whom she lied so egregiously to. She does not want her children to grow up in the shadows of her magnificent, just, valiant siblings. She is not that cruel.).
By the time she is twenty-seven – the same age she had been when she went to Narnia! – her children are four, three and two, when she tells her husband that she wishes to go back to England (it is not home as it once was because Narnia is home and Narnia is gone, gone forever) to visit her family's graves and her husband lets her go alone.
She goes to the Professor's house (it is the one thing left of her old life that she can not bear to give up, for it is the only thing left she has of Narnia). She stays there a week, and avoids the room in which there is an old wardrobe and a painting of a ship. She cries herself to sleep every night.
Why have you forsaken me, Aslan? she cries into her pillow, listening for a reply that does not come.
On the night of the anniversary of the train crash, Susan wakes up to find herself in the room, standing right outside the wardrobe. The wardrobe's door is slightly ajar.
Susan opens the door to find a Lion instead of fur coats, proud and strong and oh, so glorious.
"Come with me, daughter of Eve. It is time to go home."
And Susan follows him.
The next morning, Susan is found lying on the floor in front of the wardrobe, dead. Her husband and children mourn her greatly, (but her husband secretly hopes that Susan is with the ones she lost, home at last. He cannot begrudge her that, for he has seen the loneliness in her eyes and heard her quiet tears in the darkness).
In Aslan's Country, the four Kings and Queens of Narnia of Old rejoice at their reunion, Susan's mask (finally) undone.