Disclaimer: I own nothing Grey's Anatomy or Supernatural.

Crossing Over

John Winchester was given a second chance in life, and a second chance in love. But will his new love, Izzie, also take the chance?

"I'm sick, aren't I?" The realization hit Izzie like a ton of bricks. God, why hadn't she seen it before? It was the only thing that really made sense. There was no such thing as ghosts – or apparitions – or angels! It was all imagination.

It was all sickness.

It was everything she breathed: the sickly sweet hospital corridor miasmas, filling every pore, and bursting whenever someone touched her as she snapped back to reality.

The man – the ghost, apparition, angel – she knew as Denny reached out and touched her face gently with the back of his hand. Nothing exploded. No alarm sounded.

"Sickness is a state of mind," John said quietly, looking deep into Izzie's eyes. He had been called sick before, in his past life. He had driven himself into the ground chasing his demons by night, praying by insomniac days for a second chance so he might save his wife this time, not let her be taken away from him.

But since John had died, he had come to understand that Mary's destiny was different from his. His destiny was here – as Denny, here for Izzie. Finally, peace. Finally, love.

"Well, duh." Izzie shrugged away from him, her eyes shining. "I mean, I get it: I'm mentally ill. Thanks a lot for being more specific."

"That's not what I meant," he protested.

Izzie wrapped her arms around herself. Though the night was cold, she did so for protection, not for warmth. She wasn't sure she wanted to hear what was coming. Still, she demanded, "Well what did you mean, then?"

Denny stepped toward her squarely and gathered her up in his arms, resting her face on his chest with caring hands.

"I'm not cold," she objected.

"Yeah, and you don't need protection either." She looked up in surprise to see crinkles of laughter around his eyes. "I'm sorry, I'm not teasing you," he assured her hastily, thinking she might take his reading her mind the wrong way. "I really don't think you need protection, not from me or anyone else. You're an amazingly strong person, Izzie."

"Meaning what," she asked, "that I can beat this illness because I'm strong?"

"No," John replied slowly. "Meaning you can beat this illness because it doesn't exist." She regarded him dubiously. "Or at least it doesn't have to exist." He sighed. "We – humans – call ourselves sick, and we become sick. You called yourself sick and you immediately, unquestioningly, believed it. You could become sick – and by 'you' I mean you: your soul, your spirit, every bit of love and warmth that makes up this person who is so strong in body and heart and mind – your soul could become sick if you continue to tell yourself that you are sick."

John rested his cheek on the top of Izzie's head and breathed her in. "Once I thought I was alive," he continued softly. "I thought I had been separated from soneone I loved more than I loved myself, and like that old adage, even more than life itself. I thought we had been separated because she was dead, and I was alive." He smiled against her hair. "Sound familiar?"

Izzie nodded, understanding that he was referring to her belief that they should be separate because she was alive and he was dead – technically. Denny shifted and she studied his sorrowful but somehow also joyful face. She was surprised; she didn't know who this 'she' was. But she listened. Even if he was only a figment of her imagination and currently held her intellect captive, maybe a little bit of that intellect would spill out eventually, and give her an epiphany about how to fix her completely strange and broken life.

John swallowed hard, then resumed his story. "The fact was, Izzie, I wasn't alive. I was so full of anger and hatred and pain that I was…dead. And when I was supposed to be dead, I was suddenly alive, lying in that hospital bed, prostrated before your unconditional love. Now you think I'm dead, and I think I'm dead, and yet I'm alive."

"What does it all mean?" Izzie breathed, her head spinning with all the back-and-forth.

"It means, my Izzie, that things aren't always as they seem. You can be sick if you want to be. Or, you can open your heart to the possibility of a second chance."

She gulped.

"I opened my heart to a second chance," John said quietly, meaning Izzie. Once, he thought he would never love again. Now he knew he would love forever. "Will you?"