A/N: I'm not usually into fake dating AUs because we all know how they end and I feel that ruins the whole purpose of the fic, so I decided to make my own. My mind went straight to Alec and Lydia being awkward best friends pretending to be straight with their families and this was born. Asexual Lydia is my own head canon (and dream) so I just had to incorporate it. Also, I'm basing Lydia's sexuality off my own. Every person is different so I am no way speaking for asexuals, just me and how I understand my asexuality right now.

Chapter 1: Friday

The idea of the Fake-Date coupons had started a long time ago, but they had gone unused for close to five years since the day they were created.

Lydia and Alec had met during their first week at NYU. They were two peas, honestly, so when their outgoing and eccentric roommates dragged them to a dorm party a couple sophomores were throwing, it was no surprise that they had found each other. Neither liked to drink or had very good social skills so they had ended up spending the whole party hanging out in a random corner and talking about math, believe it or not.

Thus was the beginning of the amazing Best Friendship™ of Alec Lightwood and Lydia Branwell.

The creation of the Fake-Date Coupons was right before winter break of their freshmen year. They were hanging out in Lydia's room when she came up with the idea. It was the night before she was supposed to fly back to Chicago for Christmas break and Alec was supposed to take a cab home the day after.

They were both dreading going home, understandably. They were both returning to a life of homophobic parents and the closet life after being basically out and proud for the last few months. Alec had known he was gay since he was fourteen and had been hiding it for almost as long. Lydia was the first person he had told outright, but he hadn't been hiding it since he moved into the dorms. Lydia, on the other hand, was asexual and had no idea how she felt about relationships and affection. Half of her thought she needed someone to make out with but the other half was scared of any type of relationship stepping stone. It was a vicious, vicious cycle she was stuck in.

Lydia was lying, stretched out, on her bed while Alec sat on the floor, his back against side of the bed and his legs stretched out so far they were basically against the other bed. Alec was complaining, as always, and Lydia was doing a good job not listening to him until she suddenly sprang up.

"I have an idea!" Lydia exclaimed, rolling off the bed and basically into Alec's lap. She wretched the notebook and marker out of his hand and began scribbling on the next blank page. "So, we go home, and when our parents ask about any significant others, we just hint at each other. Nothing too specific or damning like 'oh yeah, there is this one guy who seems really nice' or 'there's a really pretty girl in my building who I'm trying to get up the nerve to talk to.' Just really innocent stuff to keep our parents off our back. But in a couple years…" she trailed off, concentrating as she ripped the paper into two coupon sized squares.

"But in a couple years," she began again, grinning at Alec like a maniac. "When we've been avoiding coming out for way too long, we use this coupon for a seemingly normal, heterosexual partner for one family function, the last hurrah of our pretend straightness."

Alec took the coupon from her hand and looked it over. He shook his head, but grinned at her. "This is literally the dumbest but greatest idea you have ever gotten. I am so in."

Since then, the Fake-Date Coupons had mostly been a running joke or completely forgotten about until two summers after they had graduated from NYU.

They had both grown up a lot since then. Lydia's classes at the police academy were about to start up, she was happily single, and best friends with Chairman Meow. Alec has been in a relationship with the marvelous Magnus Bane since the beginning of sophomore year. Magnus had basically lived with them since they rented the apartment right after graduation, but they had only officially put him on the lease a month before the whole fiasco. Life was all nice and simple until Alec handed her that damn Fake-Date Coupon she had forgotten about.

He had handed it out to her like it was going to bite him and said, "Lydia, I'm cashing it in."

"What?" Lydia had asked, taking the paper from him warily, not sure what he was handing her until she actually read it. "You still have this?" She asked him before coming back to herself. "Wait, no. Why are you cashing this in?"

Alec swayed from foot to foot, biting his lower lip and avoiding Lydia's eyes. "It's my grandmother's birthday next weekend. Her 98th birthday. It's like a huge thing. Most of my extended family is coming for the party and my mom and her siblings even rented a house so the immediate family can all stay together for the whole weekend. It's a big deal, Lyd. My grandma doesn't have much time left, this is probably the last birthday she's going to celebrate."

"I get that," Lydia said. "But why do I need to be there?"

"Because I'm my grandma's favorite and my mom thinks it will be great for her to meet and approve of my girlfriend," Alec explained, sheepishly.

"But you don't have a girlfriend," Lydia said matter of factly, almost offended by the statement. Her eyes narrowed and she glared at Alec. "Why do your parents think you have a girlfriend?" Lydia asked.

Alec rubbed at the back of his neck, keeping intense eye contact with the floor. "Because when we moved in together, they, um, kinda assumed we were together and I didn't correct them."

Lydia stood up from her seat on the couch to meet Alec's eyes. That wasn't hard, since she barely came up to his chin and he was looking down at his feet. "Alec," Lydia started once her brown eyes met his hazel ones. "Who do your parents think Magnus is then?"

Alec sighed and dropped onto the couch. "My roommate slash best friend. Basically the male you. But, Lydia, he's perfectly ok with this if you are. Seriously, we talked about this for hours. I pretend for the weekend and then I come out at Christmas. I hate this just as much as you do, but I can't just come out, my mother would kill me and think of my grandmother. If she finds out her favorite grandson is gay she might literally die from the shock. Please, Lydia. I need you."

Lydia glared at him, but it was hard to be mad at him when he felt so horrible about it. "Are you sure Magnus is completely, 100% ok with this?"

"He gave me blatant permission," Alec replied quickly. "He even wants to come and watch the whole thing go down. He thinks it's going to blow up in our faces. He's going to enjoy it."

"Ok, ok," Lydia sighed again. "When's the party?"

…

The 98th birthday party of Sofia Margarita Trueblood was a huge event. All five of her children had pitched in to rent a huge lake house for the weekend so Sofia could spend time with her grandchildren and to double as a venue for her party. Alec reported that the house would be stuffed to the top with his family the whole weekend and overflowing with extended family and his grandmother's friends by Sunday.

"I have like 12 cousins," Alec had said from his spot in the back seat on the drive up. "Plus, my eight aunts and uncles. As far as I know, they're all coming and staying Friday and Saturday night in the house. The house is going to be big but it's still going to be crowded. My family does go overboard sometimes with this kind of stuff, but it's still going to be crazy."

When Alec had explained the amount of people in the house and his family "spare no dollar for comfort" ideology, they still only expected a house, not a mansion. But when Magnus parked his car across the street from the lake house the Truebloods were renting, they were met with one of the biggest houses they had ever seen.

"Goodness, Alexander," Magnus said, leaning forward against the steering wheel to get a full view of the houses. "I knew your family was rich, but I had no idea how rich."

Alec only shrugged and got out of the car, going straight to the trunk to get out their bags. Lydia followed him, taking her bag from his hands when he handed it to her. "Are you sure you want to do this, Alec?"

"Yes. It's not even three days and then I'm back to being my regular gay self. It's going to be fine," Alec said, but it sounded as if he was convincing himself as much as her. "I'm going to be fine."

"Sure you will, babe," Magnus reassured saractically. He came up behind Alec and raising on his toes to plans a kiss on Alec's cheek. "But don't fret, I'll be there to comfort you when your whole plan blows up in your face."

"The only reason it'll blow up is if you don't quit it with the 'babes,'" Alec said, pushing Magnus's face away with his hand.

Magnus pouted. "Well, if I don't get to call you any of my adorable nicknames, do I at least get one last kiss to get me through this smoochless weekend?"

"I said smooch one time," Alec grumbled, but still did a customary look around for any wandering family before bending down and giving Magnus a chaste kiss. "And hopefully this won't be a smoochless weekend."

"Not for you and Miss Branwell, I'm sure," Magnus replied somewhat bitterly, eyes rolling. Lydia's stomach churned at the statement and Alec's ears turned a crimson red. "Oh no, don't tell me you hadn't thought of that, Alexander. You two are dating, your family will expect you to kiss at least once."

"Let's not worry about that right now," Lydia butted in. "Let's just concentrate on not getting found out before we even get past the first day."

"Great idea," Alec said, pulling the strap of his duffle over his head before closing the trunk of Magnus's car. He gave Magnus's hand one last squeeze before grabbing one of his boyfriend's bags and crossing the street. Lydia and Magnus followed behind with their own luggage in tow.

They had just started up the steps to the mansion when the door opened and a young man came out. He looked a few years older than Alec but the two were clearly related. They both had their grandfather's nose, their grandmother's striking hazel eyes, as well as broad shoulders that come with all Trueblood men. "Hey, Alec."

Alec grinned when he saw the man. "John!" he said and embraced the smaller man. "I thought you weren't coming. Last time I heard you were somewhere in Lisbon."

"I just moved back to the city a couple weeks ago. I'm surprised you didn't hear, Mom was so excited she called the whole family. And even if I didn't just get back, do you really think I'd miss an opportunity to beat your ass? Never, man," he replied before looking over Alec's shoulder at Magnus and Lydia. "Little Alec, did you bring friends?"

"Oh yeah. This is my boy- best friend. My best friend, Magnus," Alec said. To his credit, he only blushed a little bit and it was barely noticeable in the dying light.

"Smooth," Magnus whispered before Alec continued.

"And this is my girlfriend, Lydia Branwell. Guys, this is my cousin, John Monteverde."

"It's great to meet you guys. Growing up, Alec never had any friends, let alone girlfriends" John replied, shaking Magnus's hand and kissing the back of Lydia's.

Alec's smile turned force. "Just because you never met my friends doesn't mean I didn't have any."

"Sure, man," John said patting Alec on the shoulder before turning to Lydia and Magnus. "Y'know, back when my family and Alec's used to summer together, I used to steal all of Jace's girlfriends. Think I might be doing the same to Alec this year."

Lydia let out a surprised laugh before Alec cut in quickly. "Haha, that joke never gets old. It's been really nice to chat, John, but we better find my mom and get settled before it gets dark."

"Of course," John said, smiling cheekily. "I have to get get Abuela's meds out of the car before dinner, anyway. I guess the embarrassing Alec stories have to wait until dinner."

"Can't wait," Magnus said as John walked past them down the steps.

"Don't worry, Lydia, he's harmless," Alec says as he opens the door, releasing a cacophony of sounds. The house was loud when the trio stepped in. They go unnoticed for a moment, lost in the utter chaos of the house before a voice breaks through the noise.

"Alec!'

Alec took a deep breath and forced a smile when his mother appeared in the entryway. "Hi, Mom," he said shorty, bending down to embrace his mother.

"Hello, Alec." Their embrace is stiff and only lasts a moment before she turns to her son's guests. "And you must be Lydia and Magnus. Alec has told me so much about you two." Her smile looked forced and unnatural on her face, but she still pushed through. She embraced Lydia, saying what a pleasure it was to meet her before turning to Magnus.

Maryse's smile falters as her eyes travel over Magnus in his sparkly outfit and makeup. Magnus had thought against wearing his usual attire as to fit in with Alec's family, but Alec had been strongly against it. "I'm bringing my sparkly boyfriend. That way they can get used to it while they think you're just my best friend. Put on the glitter."

"Nice to meet you, Magnus," Maryse said as she shook his hand.

"Oh it's my pleasure. It's such a blessing to see where Alec and Isabelle get their looks from. I swear I thought you were Isabelle for a second," Magnus said, the charmer as always.

Maryse laughed at Magnus's words and visibly relaxed at the compliment. "Well, I am so glad you two could make it. You're rooms are upstairs. Alec and Magnus will be sharing and Lydia will be rooming with Alec's sister and her friend, is that ok, dear?"

"That's perfect, Mrs. Lightwood," Lydia replied.

"Oh, no, no. Call me Maryse, please," she corrected. "Now, go get settled. Your names should be on the doors."

…

"Lydia!"

Izzy's shriek was almost deafening as she basically dove off the top bunk when Lydia walked into her bedroom for the weekend. Lydia just managed to somewhat catch the girl, but ended up hitting her back hard against the wall and Izzy ended up on the floor.

"Oh my God, Isabelle!" Lydia groaned. "Why can't you hug me like a normal person?"

Izzy jumped up off the floor like she didn't just drop about six feet onto hardwood. She basically tackled Lydia again in a hug. "Sorry, I got excited," Izzy said, grinning at Lydia when she pulled away. "I haven't seen you in over a year, can you blame me? And where is my brother? It is completely unexcusable that I saw you before him!"

"His room is down the hall, right by the stairs," Lydia explained and then Izzy was out the door in a flurry of dark hair. "I'd knock first!" Lydia called after her although she doubted Izzy heard her. She sighed and turned to face the room again, finally notice the other girl. "Oh, hi."

The small redhead stood from her perch on the bottom bunk. "Hi, I'm Clary," the girl introduced, shaking Lydia's hand. "I'm Izzy's friend. We went to UCLA together."

"Right. Izzy told me all about you, it's nice to finally put a name to the face. I'm Lydia, Alec's girlfriend," Lydia supplied, relaxing slightly. She basically knew Clary, Izzy never shut up about Clary.

"Alec's girlfriend," Clary repeated slowly, nodding slightly like she didn't believe it but wasn't going to question it. "Izzy told me about all about you after she stayed with you, Alec, and Magnus last summer. I never really figured out which one of you was dating Alec and Izzy never said."

Lydia laughed and it wasn't forced like she thought it'd be. "Yeah, well, it's not always clear. Sometimes I feel like I'm dating both of them." It wasn't a lie, she basically spent all her free time with the couple. She doesn't know how Alec and Magnus are going to survive once she finally moves out.

"Yeah, I can understand that," Clary said, distracted and smiling at the ground.

Lydia nodded, biting her lip and staring at the ground. A moment of awkward silence passed before Lydia broke it, asking, "so I get the single bed?"

"Oh, yeah," Clary said distractedly. Lydia smiled again before throwing her bag on the bed, pulling out the things that are worthy to unpack for their two night stay.

Izzy came sliding back into the room then, long black hair billowing behind her and grinning like a madman. "So, Mom said dinner will be ready in a few minutes. Ready for the weekend to officially begin?"

…

By the time Clary, Izzy, and Lydia go downstairs for dinner, the whole family is already there. The whole downstairs bustling with the family and the caterers.

Lydia spots Alec and Magnus immediately. They're sitting in the living room, talking with an old woman that Lydia can only guess is Alec's grandmother. Magus seems to be laughing at something Grandma Trueblood said and Alec grinned when he sees Lydia, waving her over to them.

He stands when she approaches and wraps his arm around her shoulders. He's done it about a million times but it has never been awkward until now. "Abuela, this is Lydia, my girlfriend."

The smile drops off Abuela's face and her brow crinkles in confusion. Her eyes turn to Magnus and then train back on Lydia. "I thought…" she trailed off, but she composes herself quickly with a shake of her head. "I'm sorry, dear. My old mind spaces out a bit sometimes. It's a pleasure to meet you."

"Oh no, the pleasure's all mine," Lydia said, taking Alec's seat next to Magnus. Alec pulls up another chair next to his grandmother. "I've heard so much about you from Alec."

"Funny, Alejandro has told me nothing about you," she said with a pointed look at Alec.

Alec smiled sheepishly. "But now you can ask her all the questions you want."

Abuela looked unamused, but still turned to Lydia and Magnus. "So, Magnus, what are you to Alejandro?"

"I'm his best friend and roommate," Magnus said easily. "And his ride out here since neither of them have a car or a license."

"I know how to drive," Alec fired back as Jace walked in the room.

"Hola, Abuela," Jace said, butchering the words and kissing his adoptive grandmother on the cheek. "Alec, Magnus, I need your help setting up tables outside for dinner."

Magnus grumbled but stood up anyway and Alec followed, leaving Lydia and Abuela alone.

"To be honest, I thought Alejandro was dating Magnus," Abuela said making Lydia blanche and nearly choke on her own spit in her surprise.

"What?" Lydia wheezed.

"Oh, no offence to you, Lydia," Abuela said, her hand reaching out to pat Lydia's. "Just when he introduced me to Magnus I thought they were nice together. I'm sure you two are even better suited."

Lydia was spared the effort of coming up with a suitable reply by Alec's father interrupting them. "It's time for dinner, Sofia. I'm here to escort you."

"I don't need an escort, yerno," Abuela said, holding her hands out to him. "I just need a hand up."

Robert rolled his eyes but still helped her to her feet and handed Abuela her cane beofre he noticed Lydia sill sitting on the couch. "Oh, hello, you're Alec's girlfriend. Lydia, right?"

"Yes, yes," Lydia said, coming back to herself and basically jumping to her feet. "You're Alec's father. I recognise you from pictures."

Robert nodded. "Nice to meet you," he said and went to follow his mother-in-law.

Lydia fell back onto the couch and said to herself, "Holy crap."

…

The night was serene and peaceful on the lake, the silence was only broken by the laughter coming from the Trueblood family kid's table. The kids, ranging from about six years old to late twenties all sat around the table, joking and telling stories.

"Alec, want to go on a walk with me?" Lydia asked after all the food had been eaten and the plates had been clear.

Alec sent a glance at the table. Max was at one end of the table, trying to teach the younger kids some kind of card game. Magnus was talking excitedly with Izzy about fashion and the newest Project Runway season while Jace sat with Clary, the two chatting amicably and Clary smoothly brushing off Jace's flirting. With all his siblings accounted for and occupied, Alec turned back to her.

"Sure."

They both stood and Lydia took his hand, threading her fingers through his like she has seen Magnus and Alec do hundreds of times. "You have huge hands," Lydia commented as they walked towards the shore of the lake.

"Yeah, I'm proportionate like that," Alec said. "Magnus really appreciates it."

"Oh gross!" Lydia exclaimed and Alec laughed, almost falling when Lydia knocked against him. "I did not need to know that."

Alec laughed and hit his hip against hers before looking over his shoulder at the house. He let go of Lydia's hand and his hands immediately went into his pockets. "So, any reason you wanted to come out here? Or did our just miss our best friend bonding time."

Lydia rolled her eyes. "No, I wanted to talk to you." Alec nodded as he watched their feet kick up the sand as they walked. "I talked to your grandma today."

Alec humed. "I figured. I did leave you two alone to talk," Alec said somewhat sarcastically.

"Yeah, well," Lydia said, trying to meet his tone. "After you two left, your grandma… She told me she thought Magnus was your boyfriend."

Alec stopped walking suddenly and Lydia turned to stand in front of him. She crossed her arms over her chest and bit her lip as Alec stared at the sand, deep in thought. "She thought I was dating Magnus?" He asked, his thumb combing up to his mouth so he could bite the nail.

"Yeah. She seemed really surprised you had a girlfriend at all, honestly."

Alec ran his hand through his hair. "Well, she likes him. That's a good thing right? At least now I know when I do come out she won't have a heart attack from the shock." Alec's hands slid down his face. "I have never been more relieved and terrified in my whole entire life."

"She was the one you were most worried about, right? You got the hardest one out of the way," Lydia said, trying to be optimistic.

"Yeah," Alec sighed and continued walking. Lydia followed him. "Now, only my parents, my aunts and uncles, and cousins are left to disown me."

Lydia patted Alec's back comfortingly. "Way to stay optimistic, buddy."