Set after the events of 14x16, "Don't Go Into The Woods"
Jack had messed up. Messed up bad, and he knew it. He hadn't meant to hurt Stacy, and it's not like she died! She was okay!
She, Max, and Eliot would definitely never speak to him again, but she was okay, at least. That's what mattered.
And yet, Jack knew it was his powers that were to blame for it in the first place. He hadn't meant to hurt anyone. He had just wanted to make some friends. He hadn't realized that it would backfire in his face so badly.
And then Sam and Dean returned and admitted that they left him behind because of his powers. That only confirmed Jack's thoughts. He needed to learn how to control them. Until he did that, he was dangerous. Dangerous to his family.
"What about everything else? You good? I mean, anything happen while we were gone?" Sam had asked him, completely oblivious to everything that had gone down. Jack thought about telling him. Telling him that he had talked to the kids Sam and Dean had told the truth to, and that he had taught them more about monsters and how to fight them.
...And that he had nearly killed one of them by accident with his powers and a wrongly timed step forward.
But Jack didn't want to see the look on Sam's face when he realized what Jack had done. How he had used his powers, and people had gotten hurt. How Jack couldn't control them. It would only add fuel to the fire.
"No," Jack said, trying to sound convincing and innocent. "Nothing."
"Good," Sam smiled at him, and he had walked away.
Jack hadn't realized that lying to Sam would be that easy. He didn't like it, lying to his fathers. To his family, the people that he trusted. Especially to Sam, who always had faith in him. He always went to Sam for advice, knowing he could count on him to help him make the right choice, but keeping this from him just felt wrong.
But it's not like Jack could tell Dean. Dean had always been wary of him and his powers. Sure, they were fine now. Dean was just as much Jack's father as Sam and Cas were, but Dean was different. Dean wasn't the right person to tell about this, and Jack didn't want to disappoint Sam with it. The Winchesters had gone through enough. They didn't need him adding to the mess.
So Jack sat and waited for Cas to come home. But, of course, as soon as the angel returned, it was near impossible to get him alone. Cas had been on some angel business since before Sam and Dean had gone on their hunt, and he hadn't returned until now. That meant that he arrived, waved hi to Jack and Sam, and then Dean practically kidnapped him for the rest of the time.
Sam and Jack were fine with that. They just watched movies and added to the Destiel fanfiction they were writing.
Yes, they write fanfiction. In a leather bound journal, to be exact. It's hidden amongst the books in the bunker's library, where they know Dean will never find it. Sam has even added it to the card catalogue, under the word Gay.
But once the Winchesters were asleep, Cas roamed the bunker by himself. It was then that Jack decided to seek him out and tell him.
He could trust Cas with this. Cas understood what it was like to have power, to not know how to control it. He would understand Jack's problem and help him to fix, while also understand that he made and fixed a mistake. Cas was logical like that. Jack knew he had done something wrong and he felt incredibly guilty for that. Cas would see that, and acknowledge that he didn't need to be yelled at. He had already learned his lesson the hard way.
Jack found the angel in the library, reading from a leather bound journal.
"Cas?" He started. Cas promptly snapped the book shut and dropped it on the table, attempting and failing to look casual. Jack narrowed his eyes at the book.
"Is that the fanfiction book Sam and I were writing?" He questioned.
"Um," Cas said awkwardly. "Possibly."
"...Does Sam know you know about that?"
"No," Cas glanced at the book. "You don't tell him about this and I won't mention the late night sugary cereal."
"Deal."
"So what's up?" Cas asked as Jack sat down across from him. Jack stared at the table, fiddling with his hands.
"I have to tell you something," He admitted.
"Okay,"
"But I don't really want Sam and Dean to know about it."
"Why not?"
"Because Dean might get mad, and I don't want Sam to be disappointed in me."
"Sam could never be disappointed in you, although I can't vouch for Dean's temper."
"I know. I just.... I don't want any of you to be disappointed in me, and I guess I thought you were the one who would understand."
"We could never be disappointed in you," Cas reiterated. "What happened?"
"I made a mistake."
"We all do."
"It was kind of a big one."
"...Is the world ending?"
"No."
"Then we're fine. Go on."
"Well, Sam and Dean went on a hunt, and they left me here."
"Yes, Dean said he was concerned you might throw a party and trash the bunker," Cas smiled. Jack shook his head, a miserable look on his face. Cas's smile faded.
"He told me to get groceries. And when I went to get them, I ran into the kids that Sam and Dean met and told about monsters. Stacy, Max and Eliot."
"Okay,"
"And they invited me to hang out with them," Jack went on. "That's okay, right? Sam always says I should make friends, and they already know about the hunting life, so it's not like I was saying anything I wasn't supposed to, and Eliot was really interested in monsters, so I thought I could bring him some of the lore books we had. That's harmless, right? I was just answering his questions! Max and Stacy didn't really care, but they were studying for some test called the sat or something, I don't know-" Jack's rambling was slowly starting to concern Cas. He just looked so distraught as he spoke, that Cas was starting to dread what this was leading up to.
Max, Stacy, and Eliot's well being were suddenly a concern in his mind.
"But then Eliot asked me how you killed the monsters," Jack said miserably. "So I showed them an angel blade,"
"Jack," Cas whispered. That wasn't good.
"I know, I know, I shouldn't have, but I thought we were friends! And Eliot was so excited, and even Max and Stacy thought it was cool! I didn't hurt anything, I was just showing them some moves with it, and they were standing far away, so I thought it would be fine! But then I tried to throw the blade at a tree, and I missed." Jack glanced down, unwilling to meet Cas's eye. "So I tried again. And again. Until they told me to give it up. But I couldn't, you know? I knew I could do it, even if they didn't think I could, so I... I used my powers to throw the blade through the tree." Cas looked more worried now. "And Eliot thought it was amazing, so I started twirling the blade around, in like an eight shape like I do with the pencils. But then I started going faster. And faster...and faster, until they were yelling at me to stop. I don't know why I didn't, I just... didn't. But then Stacy stepped forward to stop me and-" He stopped, glancing up. "And she got stabbed." Cas sucked in a breath. "But I healed her! I did. She's okay. But now they all hate me, and they never want to see me again and I said I was sorry but they don't care, and I don't understand. I know I messed up, and I don't know how to fix it. I thought I did, but they still hate me."
"Well, I'm not exactly an expert on why humans do what they do," Cas admitted. "But I assume that they're mad because they told you to stop and you didn't, so somebody got hurt."
"But how do I fix it?" Cas sighed.
"You apologized?" Jack nodded meekly.
"A lot. They didn't care."
"Well, give them a few days and try again."
"And if that doesn't work?" Cas made a face.
"Then it might not work Jack, I'm sorry. People are unpredictable in that way. There's a chance they'll never forgive you."
"Max won't," Jack offered. "She hates me."
"Hate is a strong word-"
"She HATES me." Jack repeated. "I hate me," He whispered.
"Don't say that," Cas said fiercely. "You made a mistake, but now you're trying your best to make it right. Don't hate yourself for that."
"But it's my fault,"
"But you fixed it. Now you get to move on and let it go."
"What if I can't?"
"Then every little mistake you make will pile up inside you until you snap and do something stupid. That's what happens to Dean. Do you really want that?"
"No."
"Exactly. It's okay, Jack. You didn't mean to hurt Stacy, and you fixed it. I can't help it if they don't forgive you for that, but one day they will appreciate the fact that you saved her. That's all you can do for now." Jack frowned.
"I hate that."
"I'm afraid it's apart of life, Jack. Just another thing we're all still getting used to."
"Are you going to tell Sam and Dean?"
"No," Cas admitted, rising from his seat. "But would you prefer it if they heard it from you now, or from Max and Stacy?" Jack's eyes widened. "Exactly. Good night Jack."
"Good night Cas." The angel headed off. "Cas?"
"Yes?"
"Thank you." Cas smiled at him.
"Anytime."