Authors note: This is the first part of this series, We've Been Living on a Fault Line. This isn't set at a particular time in the show, it is an AU—JJ never started dating Will and Henry isn't a fixture either. The only part that's really canon is the appearance of Sergio.

Song inspiration: 'til Forever Falls Apart by Ashe and FINNEAS.

Disclaimer: I don't own any of the characters and/or the established storyline, they are credited to the writers and creators of the show.

Synopsis: JJ is kept behind at work by Penelope. Little does she know there is a surprise waiting for her at home.

I'll Be Yours Forever

JJ exhaled a sigh of relief as she closed her last file. After four mind-numbing hours of paperwork, she was finally done; she hoped she could escape the bullpen before Penelope could dump another case on her. Everyone else on the team—apart from Hotch, who pretty much lived in his office—had left well over an hour ago, and it was starting to frustrate the blonde agent.

In the five seconds it took for JJ to reach under her desk for her bag and stand back up again, Penelope appeared out of nowhere, and the agent yelped in fright. Penelope stood next to JJ's desk, files in her arms and a cheeky grin across her face.

"Don't tell me there's another case," JJ groaned. There was no doubt that JJ loved her job, they all did, but all she wanted was to go home. "I can't take any more."

Penelope grabbed three folders, placing them on JJ's desk. "Just making the rounds for the morning."

"Oh thank god," JJ swung her jacket over her shoulders and pulling it tight, "I was ready to fake an emergency to get out of here."

"You wouldn't dare."

JJ hummed. "Are you sure you want to take that bet?"

JJ bolted out of the bullpen and into the elevator before Penelope could respond; she was eager to get home to Emily and Sergio, ready to do absolutely nothing for the rest of the evening. As she rode the elevator, JJ hoped that Emily was in the mood for takeout. The younger agent was craving her usual from the Chinese restaurant that was two blocks from the apartment.

When she jumped into the car, JJ called Emily to let her know she was on her way home finally. Emily hadn't answered the call, which wasn't unusual; JJ assumed she was either cooking dinner or showering or, better yet, fast asleep on the sofa, in which case she knew she would join her.

Since the traffic from Quantico to the apartment had been virtually non-existent, JJ had arrived home in record time. Parking in her usual spot, she turned off the engine and grabbed her belongings from the passenger seat. When she was two steps from the car, she turned back, grabbing as many travel mugs as she could carry. Both her and Emily always forgot to bring them in, and there was only one left in the cupboard, and they were essential for their morning coffee; JJ knew Emily would fight her over who got to use it.

With a bounce in her step and her hands full, JJ finally made it to the apartment. It was later than she would have liked, especially since most of the team had already been home over an hour, but she was happy to have an evening to relax.

"I'm home," she shouted as she entered the door. JJ kicked her shoes off, dumping her keys and the travel mugs on the side before she hung her jacket. Sergio came running down the hall and started purring at her feet. "Em?" she shouted once again when she didn't get an answer.

"In the kitchen!"

JJ bent down to pick up the cat, kissing his head and scratching behind his ears as she walked down the hall. Before she could enter the kitchen, Sergio began to struggle in her arms, so she lowered him to the flood and grinned as he darted through the small gap in the open door.

As the scent of food wafted from the kitchen, JJ took a deep breath and came to a complete stop as she opened the door. Emily stood in the kitchen with a bouquet of sunflowers and red roses in hand and a big smile on her face. The table to the left was lit up with candles and in the middle was an ice bucket with a bottle of JJ's favourite wine.

"Baby?" JJ said softly, inhaling deeply to smell the flowers. "What's all this for?"

"Can't a girl just cook dinner for the woman she loves?" Emily said.

As JJ placed a quick kiss on Emily's lips, the entirety of her evening suddenly fell into place. "Is this why Pen kept giving me cases that urgently needed doing?"

"I'm sorry," Emily laughed.

JJ lightly punched Emily on the arm, her smile wide as she laughed. "You are so lucky I love you. Penelope's gonna get it tomorrow, I swear."

Dinner had been exquisite; grilled chicken with a side of roast veggies and mashed potato had always been JJ's favourite. She still wasn't sure what she had precisely done to deserve all this; she knew for sure that she hadn't missed an anniversary and her birthday wasn't until next month, but she didn't care.

The job that they had signed up for came with a lot of sacrifices, one of which left both Emily and JJ with little personal time. They knew they were lucky, they got to work together and come home to each other, it was more than what other couples in the Bureau had. Even so, there wasn't many instances when they could do something like this for each other, and the fact that Emily had gone out her way to organise this while also being swamped with work showed JJ just how much the other woman loved her.

When she was sure that Emily was done eating, JJ reached over to grab her girlfriends plate; as a rule, she always made sure to clean up when Emily cooked and vise versa. Before JJ could take the plate, Emily stopped her with a soft hand on her wrist.

"That can wait," she insisted. "I need to talk to you about something."

"I missed an anniversary didn't I?" JJ said quickly. "I am so sorry–"

Emily laughed and shook her head. Standing up from the stable, Emily held out her hand. "You didn't, but come with me."

Taking Emily's hand, JJ allowed Emily to guide her into the living room and towards the giant windows at the other end of the room. JJ had always loved the view of the city from Emily's living room; she often found herself with a glass of wine in hand and enjoying the life that bustled through.

A year ago, when Emily had asked JJ if she wanted to move in together, the younger woman had agreed but only if they could live in Emily's apartment; there was no way she wanted to give up the view. Emily had laughed at her girlfriend's insistence before kissing her passionately.

"What's going on, Emily?"

Emily's heart started to beat a little faster than she would have liked. She had talked guns out of the hands of unsubs without breaking a sweat, but somehow in the comfort of her own home, with the woman she loved in front of her, she was more nervous than she thought she'd ever been in her life.

"I love you, Jennifer, more than I'll ever be able to tell you," she said.

JJ squeezed Emily's hand, her head tilting to the side as she smiled. "I love–"

"Please, let me finish," the older agent interrupted; when JJ silently nodded, Emily took a deep breath. "I always thought I'd be better off alone, without friends and family; I was used to it. But then I started at the BAU, I was ready to keep my distance from you all but everyone showed me that it wasn't so bad having people to count on, for some backup when I needed it. You guys became my family without even trying." Emily ran her fingers through her hair and smiled. "But then there was you. You were different. You saw through me, through all my bullshit and even though it sounds stupidly cheesy, you turned my world upside down."

"Hey, I love cheesy," JJ said defensively with a laugh.

"You showed me that it was okay to love, to have someone to wake up to every morning. When you love me, the way you love me, I always feel like I'm floating." Emily reached into her back pocket, pulling out the ring that had been burning a hole since JJ had gotten home. "I want to feel like this for the rest of my life," Emily knelt on the floor, holding the ring up. "So, if you'll allow me, I'd love to spend a lifetime giving you my heart. Will you marry me?"

JJ took a step back, her hand covering her mouth, nodding furiously. "Yes, yes!" As Emily stood back up, JJ threw her arms around Emily's neck. "I love you, Emily Prentiss, so much."

"Here," Emily said, stepping back a little. She took JJ's hand, putting the ring on her finger.

JJ couldn't help but stare at the rock; she had no idea this was how her night was going to turn out. Looking up, she couldn't help but fall a little more in love with the excitement that shone in Emily's eyes or the shy smile that graced her full lips, the smile that was reserved only for her.

The younger woman stepped forward, her hands cupping Emily's face as she brought their lips together. Each kiss felt like the first time; there had never been a time in either of their lives where a simple kiss was filled with the amount of love they had for the other.

Pulling back, JJ smiled. "I swear, no matter what, I'll be yours forever, 'til forever falls apart."

"You're so cheesy," Emily laughed, kissing JJ again.

"You love it."

"I do."

"Too early," JJ laughed.

+/+\+

The ride to Quantico the next morning had been spent debating who would notice the ring on JJ's finger first; Emily had insisted that Morgan or Reid would be the first, but JJ knew that Penelope was an expert in spotting things that were out of the ordinary, and she was sure the blonde knew more than she was letting on last night. When they couldn't decide, JJ came up with an idea.

"Wanna bet on this?" JJ asked.

Emily looked over with a smirk. "Are you sure you want to lose?"

"Oh, I'm not going to lose," JJ said quickly. "How about two days worth of paperwork?"

"You're on, Jareau."

A few minutes later, Emily pulled into the carpark under Quantico and the women walked together towards the elevator. As the elevator reached the sixth floor, Emily gave JJ's hand one last squeeze before they exited. Emily pulled open the door, letting JJ walk in first.

After putting their bags at their desks, the women walked over to join Morgan, Reid and Penelope in the small kitchen for their morning coffee. The three were already huddled over a single newspaper and talking over one another.

"Are you guys reading horoscopes?" JJ asked, hurrying to join the others; she had never really believed in horoscopes, but they were always fun to read.

"Oh, come on! There's no way any of you believe in that stuff," Emily said with a huff.

"Gemini seems accurate," Morgan said with a grin. "I've always got the magic ingredient."

"Horoscopes aren't as inaccurate as you might think," Reid said, "Although there is more to it than your birth sign–"

"We got it, Spence," JJ said.

"All right, Emily. What's your sign?"

"No. Absolutely not," Emily deadpanned, walking past the others to get to the coffee machine.

"Jayje?"

"I got this." JJ smiled when Emily glared at her as she took the newspaper from Penelope, giving it a quick straighten before she started to read. "Any secret plans hatched with a pesky blonde which will lead to all your dreams coming true."

"Huh?" Penelope said with disbelief. "That makes– JJ that makes no sense, give it back to me."

JJ folded the paper with a smirk, handing it back over to Penelope with ease, her eyes never leaving Emily's. As the blonde took the paper, JJ made sure to flip her hand a little to make sure she'd see the ring. As a result, JJ almost jumped when Penelope grabbed her hand and let out a squeal.

"You're engaged!"

"No, that's against the rules. You lose the bet," Emily said, pointing a spoon at JJ.

"What bet? Who cares about the bet? JJ and Emily are engaged. We're going to have our first wedding!" Penelope babbled. "I call dibs on being maid of honour. We need to–"

"Baby girl," Morgan said, putting reassuring hands on Penelope's shoulders. "I think you've had a little too much caffeine this morning."

Both Morgan and Reid hugged JJ, congratulating her on the engagement and Penelope apologised for going along with Emily's plan to keep her behind at work. But before anyone could get into specifics about the engagement, Hotch called them into the round-table room.

"We have a case in Colorado," he said, holding up the case files.

While Morgan, Reid and Penelope walked ahead, JJ stayed behind and waited for Emily.

"You know this doesn't count as a win, right?" Emily said, passing over a mug.

JJ pursed her lips together in a sweet smile. "Sure it does."

"You are so in for it when we get back," Emily said quietly.

Before they entered the round-table room, JJ gave Emily's arse a quick squeeze. "I wouldn't have it any other way, Prentiss."

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