After Serenity, Kaylee and Simon are happily together for a few months. But something is just not the same. There is a haunted look in her eyes, her smile is not quite as shiny as it used to be. A new guy is hired to be the pilot of Serenity, his hair is blonde and sometimes, just for a moment, she sees him in her peripheral vision, and he almost looks like Wash. But he's not. Kaylee knows she will never hear his warm voice or laugh at his jokes ever again.
She worries. She worries about everyone in the crew, especially Zoe. It's in Kaylee's nature to be kind and happy all the time, but she finds herself swallowing her true thoughts and emotions to better look after everyone else.
She immerses herself in work, spending her days in the engine room, fixing things that don't need to be fixed. Simon notices the determination in her eyes, he knows what she is trying to do - trying to forget. He has often seen River like this, and it alarms him that Kaylee is going down the same dark path. But he has never been good with words. He doesn't say anything.
One day, Zoe decides she's had enough of this 'new' Kaylee. She brings her to the wheel of Serenity, and they both look out into the 'verse.
"You don't need to worry about us, Kaylee. Especially me. When I feel lonesome and I miss Wash, I come in here and look out this window, knowing that somewhere out there in the 'verse, there's trouble need fixin', and Wash will lead us there. Because he's been at this chair for so many years, his memory ain't leaving there anytime soon."
Zoe's words stay with Kaylee, and each day for a week she waits for the new pilot to take a break, then goes to sit in the pilot's chair. She can almost hear Wash's voice, and she sees his toy dinosaurs next to one of the consoles. Somehow, this gives her room to heal. Soon, she is smiling vibrantly again, returning Simon's kisses with real passion.
The haunted look in her eyes fades as she learns to be happy again.