Summary: AU. Even the best of us can get possessive. When Castiel gets together with the girl of his dreams, he starts to become insecure, and things go from bad to worse. Can he get past his fear or will she leave him before he truly hurts her? Please R&R!

Disclaimer: I don't own Supernatural or its characters. I only own my OC.

(PLEASE READ!) A/N: Dark themes are coming with this fic, a side of Cas you might not like along with a girl who becomes frighteningly vulnerable.

I really hope you enjoy it and I'd love to know what you think so far and if you want me to continue.

Thanks for taking the time to read this first chapter and I really hope you like it.

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Possession

~Chapter One: It Starts With Small Things~

Castiel had never seemed the type to become insanely possessive. It just wasn't in his nature, yet when people found out the truth about what had been happening between him and his girlfriend, they were truly shocked. Some were upset, others were disappointed and a few were just plain angry, because what Castiel had become was far from the person he'd been brought up to be, far from the person they all knew so well.

It starts with small things, like maybe a guy will notice other men checking his girl out because she's got most of her legs on show, or a lot of her chest on show, and he'll get so pissed he'll start saying he doesn't like it when she wears short skirts. He might start to check her cell phone because she has a lot of friends who are men and he fears she's cheating on him. He might ask his girl if she really needs to go out with her friends.

Then it progresses. Then it becomes more noticeable, like asking her what she's being doing while she's been out, calling her every hour or so, maybe. He might start to throw accusations about, imagine that things are happening that really aren't. Then he might start telling her what she can and can't wear, or what to time to come home for, or even who she can and can't see. Following that sometimes comes anger and violence towards her that she totally doesn't deserve, all because he's so scared of losing her.

Castiel always thought that Eleanor Miller was way out of his league, was way too good for him. But on their graduation day from college, he'd finally gotten up the courage to tell her how he felt about her and she'd reciprocated his feelings with a kiss that had blown his mind completely. They'd been together for six months now, and were walking home from a night out.

They'd been to a club with their friends, Dean and Pamela who'd been a couple since senior year in high school. The group of friends that Castiel and Eleanor had was a lot bigger than just Dean and Pamela. All fourteen of them had been friends for as long as they could remember and were still as close as they were in high school. Pamela and Dean crossed the street to head towards their apartment while Castiel and Eleanor headed their own way home.

As the couple walked down the street, Castiel looked down at Eleanor, taking in how beautiful her blonde curls were as they rested on her shoulders, how gorgeous her stunning blue eyes looked as they were dusted with a hint of purple eyeshadow to match her outfit. She was wearing a dress tonight and she looked so stunning that it was unbelievable to Castiel. She seemed to be more beautiful and more amazing every day, and they'd been living together for two weeks which meant Castiel got to wake up beside this wonderfully gorgeous woman every morning, got to come home to her every day and fall asleep with her in his arms every night.

But as the four friends approached Castiel and Eleanor's house, Castiel spotted someone who he remembered vaguely from school, one of the bastards who used to try and torment him on a daily basis. The guy, Alistair Masters, looked Eleanor up and down and wolf-whistled, checking her out as they walked by even when he saw Castiel holding her hand.

"Nice ass, sweetheart!" He yelled, Castiel gripping Eleanor's hand tighter which made her wince in pain, the nostrils of her gorgeous, straight nose flaring as she did.

"Cas...Cas, that hurts..." She breathed, Castiel gasping and loosening his grip.

How dare that bastard wolf-whistle his girl and then speak to her like that? How dare he? Castiel was ready to go and give the fucker a good ass-kicking but Eleanor caught his attention as they stopped by the gate to the front yard.

"I'm sorry..." He breathed, taking her hand and rubbing it gently, "I'm sorry, did I hurt you?"

"It's okay..." Eleanor replied, "Just don't get so worked up over guys like him, okay?"

Castiel nodded, earning a sweet kiss from Eleanor as they headed into the house, the twenty-two year olds heading straight upstairs to bed. They got ready for bed in the bathroom together, Castiel getting into bed first and going over what had happened on the way home. When he thought about it, a lot of men looked at Eleanor that way, but none of them had said something like that to her. He was furious, and he wondered if it was because Eleanor often wore short dresses. He didn't like the idea of other men having sick fantasises about his girl after getting a good look at her exposed body as it was in that dress, how defined it was by the tight fabric and how much flesh was revealed.

He looked up as she left the bathroom and sighed at how beautiful she looked even in her vest and shorts that she wore for bed. She looked at him and sighed herself, turning off the bathroom light and climbing into bed herself before cupping his cheek.

"Sweetie, are you still mad at what Alistair said?" She asked, Castiel blinking in shock.

"You remembered who it was?" He countered, Eleanor chuckling in response.

"Of course I do, Cas. He used to torment us every day in school...that sick fuck." She replied, "Listen, don't let it get to you, alright? He's just a stupid ass who thinks he's still fifteen."

"M'sorry, Elle." He whispered, "I just hate people speaking to you like that, and about you like that."

"Cas, it doesn't matter what anyone else says to me...I only care about what you say to me, okay?" She whispered, "I love you, and you're the only one who matters."

With that, she kissed him gently and stroked his cheek again, showing him just how much she loved him with one look before turning out her light. Castiel did the same and took her into his arms, pressing a kiss to her forehead.

"Thanks for the amazing night." She said softly, "I love you."

"I love you too." Castiel whispered, "Goodnight, Elle."

"Goodnight, Cas."

As they settled to sleep, Castiel couldn't stop thinking about the amount of men who had disgusting thoughts about his Eleanor when they saw her in the street, how there were men who they passed when they were out who Eleanor could easily be happy with instead of him. She was too good for him and all this seemed too good to be true. Someone like him didn't get a girl like Eleanor. But what Castiel didn't understand was that Eleanor thought he was the most precious and amazing thing in the world, and that she felt she wasn't good enough for someone as sweet or gentle as him.

He'd begun to feel like he constantly had competition for her around him and no matter how much she reassured him she loved him more than anything, he still couldn't get the nagging feeling out of his head that he could lose her to any guy around him, and a lot of their friends were men which made him even more wary, especially Crowley who'd always been up for a flirt with Eleanor. Castiel hadn't minded before but after his revelations over the past few weeks, he'd be keeping an eye on how that little flirting session went.

God, what was happening to him?

-TBC-

So it begins...

Hope you enjoyed!

Thanks for reading so far and please review!

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