“Did it hurt, Your Majesty?”
“Excuse me?”
“Did it hurt?” Alastor repeats, leaning closer with a leer.
“Did what hurt?” Lucifer replies, thoroughly perplexed. He tries to remember if he’d done anything that might be considered painful, recently.
Alastor’s grin turns mean—sinister, even, as his voice crackles with static. “Why, when you fell from Heaven, of course!”
—
Alastor gets cocky about harassing Lucifer, flies a little too close to the sun, and they both learn some things about themselves.
(The original Adam Redemption/Adam Agenda fic)
After the last extermination, Adam survives but is cast out of Heaven and sent to Hell. Charlie encounters him and learns there's more to the story she was told growing up. Adam wasn't always the villain he was portrayed as and her parents weren't the heroes she believed them to be.
This is the story of Hell told by the man who used to have everything. And his tragic downfall where he lost paradise not only once, but twice.
Many sinners will tell you just how frightening the King of Hell truly is. From the way he holds himself up in battle to the way he loves his daughter and wife. That's what the public said, anyway. He had to make Charlie happy. He had to, there was no other way about it. She was in fact his everything. He couldn't risk losing her again. Even if risking revealing the worst parts of himself to an unexpected, annoying, self-centered, certain Overlord.
"Lucifer could still remember the first time he’d seen Adam. Vividly. It was one of those memories that never quite seemed to fade. That tilted its head up in defiance at the cruel hand of time and stood its ground, refusing to be dulled by something so trivial as eternity.
He had been beautiful."
or
An AU where Adam and Lucifer knew one another a bit more intimately during their time in Eden (and what comes after).