Castiel's eyes widened when he saw Elizabeth standing behind the Hunter. He pulled his angel blade out of his coat and lunged for the redhead when Sam suddenly stopped him, jumping in front of the angel. Elizabeth flashed a smirk and Castiel looked at Sam in confusion.

"Put the blade away. She's with us, Cas." Castiel glanced between the demon and the Hunter.

"She's working with Nadia," Cas argued.

"Was working with Nadia," Elizabeth corrected. "The bitch has no need for me now that she has Libby. Besides, I want to kill her just as much as you do. It'll be a lot easier if we work together." Eliza took a step forward. "Listen, Angel, I'm willing to play nice if you are, too." Castiel frowned slightly and looked over to Sam.

"Does Dean know about this?" Sam shook his head.

"No. Dean left, remember? Besides, who knew what he'd do if he found out we're working with Libby's demon half." Cas looked back to Elizabeth who grinned at him. She held her hand out for him to shake.

"Call me Eliza." Cas eyed her hand warily and took a step back. Frowning slightly, her hand dropped to her side and she cleared her throat. "What do you need me to do? I assume we don't have any plan on how to track Gadreel yet?" Both Sam and Castiel shook their head.

"No, uh..." Sam scratched the back of his head in thought. "Why don't I make us breakfast—"

"It's lunch time, honey," Eliza corrected. Sam sighed. He'd slept in later than normal.

"Okay, I'll make us lunch and then we'll hit the books. Sound good?" Castiel and Eliza exchanged glances before shrugging. Sam clapped his hands together, giving them a thumbs up, before retreating back to the kitchen. The moment he left the room Eliza was shoved against the wall, angel blade held against her neck. She let out a grunt and looked up at Castiel.

"Huh. Didn't think you had it in you, Feathers," she muttered.

"What is with demons and nicknames?" Eliza just shrugged. She reached out to grab the blade when Cas pressed it further against her neck, a drop of blood slipping out. "Don't," he warned.

"Careful there, Trench coat. You kill me then you kill both Libby and this vessel. You didn't think that I just magically got another body, did you?" Castiel raised his chin slightly and eyed the body. She was right. It wasn't Libby's body. None of the mysterious tattoos were there and some scars were missing, too. Cas rolled his eyes and pulled the blade away, letting Eliza go roughly.

He watched with piercing blue eyes as she ran her hand across her neck, the wound magically healing.

"Gotta keep Kit Kat up and going. She's an actress, I hear," Eliza said with a smirk before turning on her heel and making her way to the kitchen where Sam was. She left Castiel standing there with a defeated and pissed off look and a clean angel blade. Neither celestial being wanted to work with each other but if they wanted to find Libby and Gadreel then it was something they'd have to do.

~*~

After realizing that there was no food to make, Sam went out to get some groceries leaving Eliza and Cas in the Bunker. Alone. They had argued for the first fifteen minutes but settled it when the redhead suggested that she make the angel a peanut butter and jelly sandwich.

As the two sat across the table from each other, Castiel took a bite and cringed in disgust. Eliza frowned slightly.

"Oh, come on. I know Libby was a bad cook but this is a sandwich!" the demon exclaimed. Castiel shook his head and finished chewing, setting down the sandwich on the plate.

"No. It tastes like...molecules."

"What? What are you talking about?" Eliza and Cas looked up to see Sam walking down the stairs with two grocery bags in hand. Eliza grinned at the sight of the Hunter and Cas just watched him. Eliza snatched the sandwich from his plate and took a bite. She spit it back out instantly. It did taste like molecules.

"When I was human, you know, I had to eat constantly. It was kind of annoying," Castiel explained.

"Yeah, a lot of human things are pretty annoying," Sam agreed.

"But...I enjoyed the taste of food—particularly peanut butter with grape jelly, not jam. Jam I found unsettling," Cas added. Sam set the bag down and sat on the table next to Cas, swiping his finger across some peanut butter on the side of the plate.

"So, what? Now you can't taste PB and J?" he questioned. Cas shook his head, licking jelly off of his finger.

"No, I-I taste every molecule."

"Not the sum of its parts, huh?"

"It's overwhelming." Sam chuckled. "It's disgusting." Cas stared longingly at the half-eaten sandwich. "I miss you, PB and J." Eliza chuckled, hiding her hand behind her mouth, as Cas stood up. "We need to continue your healing. We're almost done." Sam closed his eyes and lowered his had slightly as Cas lay two fingers to his forehead and started to heal him. Suddenly he looked a little concerned and Eliza leaned forward and watched with intrigue.

"What?" Sam asked when Cas didn't say anything.

"Nothing."

"You're a terrible liar," both Sam and Eliza chimed. Sam sent her an odd glance but she only smirked, licking her lips. Cas scowled at Sam.

"That is not true. I once deceived and betrayed both you and your brother." Sam sighed and rolled his hazel eyes, ignoring Eliza.

"Okay, that's not the point. Cas, what's wrong?" the Hunter demanded.

"I noticed something. It's, uh... It's resonating inside you." Sam looked up, eyes wide.

"What?"

"Something angelic." Eliza stood up, walking over to the two men.

"Okay, uh, what the hell does that mean?" she asked, her voice stern and full of worry. Cas eyed her in confusion. He wasn't sure why she would be so worried about Sam. They were only taking advantage of each other to find Nadia, Libby, and Gadreel.

"Maybe we should call Dean," Cas suggested. Eliza's green eyes widened and she looked down at Sam who moved away and sat down in a chair next to him.

"No. He wanted to go, and he's gone. We'll handle this." The brunet pulled a lore book towards him and Eliza and Cas exchanged glances. Cas grabbed onto her arm, pulling her out of earshot.

"What are you doing?" the demon growled, yanking her arm back from Castiel's grasp. He seemed to search her eyes for something before he recoiled in shock. "What?"

"No. It's not possible."

"What's not possible? Castiel, you're really starting to piss me off. I understand that you don't want to work me and that's fine but—"

"You're in love with him." Eliza shut up and took a step back, staring at Cas with wide eyes. They seemed to have a hint of fear in them, but Castiel wasn't sure. He didn't know what parts of Libby were in Eliza. "With Sam. You're in love with Sam."

"Wha—"

"You said that you two were soulmates. It makes sense." Eliza ran a hand through her hair and turned around, trying to get her breathing under control. If Cas found one of her weaknesses then she knew she was in trouble. As a demon among Hunters and angels, she had to do everything in her power to have the advantages. "You're not staying because you want to find Nadia, you're staying because you want to be with Sam."

"I'm staying because you guys are the only way I can find Nadia and kill her without me dying in the process!" Eliza roared, spinning around to glare at Castiel. He didn't flinch or show any sign fright or weakness. She sucked in a sharp breath and recomposed herself. "Sam can't know of this. He'll think that the only reason I'm staying is to get to him. Right now you two are my only option at defeating Heaven's Demon and I'm gonna take it."

"Fine. But the moment you—"

"Yes, I know. You've made yourself clear." Eliza glanced over her shoulder at Sam. "We better go help him. The faster we work the faster we find Gadreel." With that she made her way back to the Hunter, sending him a small smile as she took the seat on the other side of him. Cas took his old seat back and pulled a book towards him, sending Eliza a wary look.

~*~

Sam and Eliza were looking through different books in the Bunker library, Castiel flipping through his own book in his grasp. Eliza let out a bored sigh. If this was how it was going to be for the next couple of days then she wasn't sure if she could put up with it. The books she was educated from had been enough for a lifetime.

"I've found, well, something." Both the Hunter's and the Demon's heads snapped up at the sound of Castiel's voice and they raced over to the bookshelf that separated them. "It's a detail about when angels leave their vessels...I think. It's, uh, Enochian, which can be a bit flowery. 'And the departed shall remain, and the remains shall be the departed'," the angel read. Cas stared off in front of him, processing the words.

"Okay, so, when an angel leaves a vessel, they leave behind a piece of themselves. Like, uh...like an angelic fingerprint," Eliza said. Cas nodded, glancing back down at the book and refusing to meet Eliza's gaze.

"Whatever you want to call it, this piece of the departed contains Grace," he replied.

"Wait, you're saying there's angelic Grace inside of me?" Sam questioned. Eliza nodded, turning to look at Sam.

"Yes. But it's fading each time he heals you," she told the Hunter.

"Okay. Is that good or bad?"

"Well it's harmless. But the Grace itself... might be helpful." Cas slammed the book shut and set it down, walking over to a table and picking up a file titled 'On the Inner Workings of Angels'. Sam and Eliza walked over to study the file in Cas' hands. "According to this, we may be able to use the Grace that remains inside you to track Gadreel...If we can extract it," he explained.

"How would we do that?" Sam asked, crossing his arms over his chest as he skimmed over the paper. Eliza gulped when she saw the size of the needle in the picture. That would definitely hurt a human, accustomed to pain or not.

"Well...painfully. The Men of Letters believed that you could perform a tracking spell with extracted Grace, but they were never able to test the theory." Sam nodded his head to the side, his hands now on his hips. Eliza looked over to Sam and studied him. He was about to agree. He was seriously about to agree to this experiment.

"Well, they didn't have a guinea pig, but we do," Sam said. Cas stopped and furrowed his eyebrows, looking up.

"You have a guinea pig? Where?" he asked, almost eager to see the guinea pig. Eliza let her head fall into her hand and Sam stared as Cas in disbelief. He had been on Earth and around humans longer than Libby and Eliza ever had been, yet he still failed to grasp the way they think.

"Me, Cas. I'm the guinea pig," Sam said as if it were obvious. Cas glanced in front of him, realization hitting.

"Oh." Sam took a closer look at the drawing of the needle before flipping the page up to see an actual photograph. "Any idea where that is?"