The first thing Sam does after Lucifer dies is call Rowena. She picks up after two rings.
“Hello, Samuel. Are you calling because you’ve found the wee angel lad?”
“Lucifer’s dead.” The words don’t seem real coming out of his mouth, seem too good to be true.
There is a long pause from Rowena, then she makes a kind of strangled noise in the back of her throat. “Are you su—”
“He’s dead, I watched it happen. His wings are burned on the floor.” There are still a few embers burning.
“Oh my god. Oh my god.”
“Where are you?” she demands.
“St. Mary’s Covenant in Ilchester, Maryland.” How perfectly fitting, for Lucifer to die in the place where he was first set free.
“I’ll be there in two hours.” She hangs up.
Sam has no idea how she’s going to get there so fast (she has to be more than two hours away), but he figures it probably has something to do with magic, and maybe some raw determination.
She arrives exactly when she said she would: two hours on the dot. She throws the doors open so hard that they slam against the walls and bounce back. Rowena runs into the church, through the pews, and stops dead when she sees Lucifer’s corpse.
Slowly, she approaches it. She leans down and puts her hand on his chest, closing her eyes as she does so. When her eyes open again, they are brimming with tears.
“He’s dead,” she whispers. “Really, truly dead.”
“Yeah.” he says, and he thinks he might be crying.
“Thank god,” she gasps. “Thank god.”
And then they are hugging, holding each other, crying on each other. It’s all such a relief: Lucifer is dead, and Sam gets to celebrate with someone who suffered like he did. With someone who understands.
It is a long time before they stop crying, and even then, they don’t want to be the first to let go. Jack makes the decision for them when he says, quietly and plaintively, like a small child, “Can we go home?”
“Yeah,” says Sam. “Let’s go home.”
As they leave the church, Rowena asks, “Where’s Dean?”
Sam freezes. Dean. Oh my god, Dean.
“Michael,” he chokes out. “Michael’s here, in our world, and he’s got Dean, he’s, he’s—”
Rowena grabs his shoulders and shakes him gently. “Sam.”
Sam stares back at her helplessly. He isn’t supposed to feel helpless anymore. Lucifer is dead.
“We can save him. I don’t know how, but that monster in there—” she gestures towards the church “— is dead. There’s nothing holding us back. We’ll save your brother.”
“Okay,” says Sam. And he starts to feel hopeful again.