Billie's been preparing for this for a long time - she's seen how this ends and wants the Winchesters to win, but of course, they're not there yet. They still have a lot to do first before they get there. Team Free Will has to work for the ending they deserve.
She saw Jack's second death coming for weeks and talked to the Empty about it - the nephilim won't be going to Heaven this time because he has a purpose. Like his fathers before him, his death isn't permanent. Billie is ready to fight God and reap him to save the world.
Billie's already waiting in the Empty, cringing in anticipation of all the souls escaping Hell (and Heaven, soon) when Jack comes to with a gasp. "About what?" he questions when she tells him they should talk.
"About the problem Chuck - God - just unleashed upon the world because the Winchesters didn't follow his script."
"What problem?" Curious despite the situation - he's dead again but doesn't feel empty again - Jack has to know.
Billie sighs. "He just released all the souls from Hell - and Heaven's thisclose to finally falling - expect that to happen any minute now - and unleashed a horde of zombies on the Winchesters and Castiel. I don't like 'Team Free Will' repeatedly fucking up my plans with their numerous resurrections but it's necessary in this case. You are needed to help them stop this apocalypse, Jack."
His mouth drops open. "Me? But why me? I just killed Mary! And a bunch of other innocent people!" Is he starting to feel again?
Her mouth quirks. "And Dean couldn't kill you, right? And to answer your question, your soul's slowly coming back. We have to hurry and finish this conversation because the zombie horde is about to kill your fathers, by the way. Can't dawdle. Or fuck anything up, but I know who I'm talking about, so that's off the table."
Jack does laugh at that. "Why are you so interested in saving the world? I thought you hated us."
Billie shakes her head. "Far from it. Chuck can't just end this world on a whim - I won't allow it. Despite what he may think, he's not the ruler of the Universe."
From behind her, the Empty taps its wrist, urging her to hurry up.
Jack is suddenly feeling everything and hates himself for killing Mary, for the way he treated Sam and Dean afterwards. He understands so much now. "Fuck," he murmurs and then his eyes dart towards Billie, expecting her to chide him. He might have picked up on the Winchesters' language but in his defense, so has Castiel.
She rolls her eyes in fondness at him. "Time to go, young one. You have work to do."
"Thanks, Billie." Strolling up to Death, he hugs her, catching her off guard.
Billie only pats his shoulder. "How … sweet. Tell them there's a plan, got it?"
"Got it." Jack pulls away and takes a deep breath to prepare himself for his resurrection.
Billie winks and then points her scythe at him, prompting Jack to blink from existence in the Empty.
Chuck may think he holds all the cards but he's underestimated her - and Team Free Will, of course. He doesn't know what she's truly capable of, which is how Billie likes it.
The song doesn't have to remain the same.