"So, if Andromeda and Ted have a kid, it'll be a half-blood, right?" Remus asks the Marauders, Sirius nods.
"Yes, because Ted's a muggle-born and Andromeda is, obviously, a pureblood."
"Or a liar," James suddenly says in a weird voice as he slowly looks up from his game of exploding snap, the others look at him like he's an idiot, including Frank, his snap opponent.
"…no, she's definitely a pureblood."
"Or a good liar."
"James, for Merlin's sake, she's a Black."
"A very good liar. Got you all fooled, doesn't she?" Sirius looks at his friend for a minute before he just gets up and walks into the dorm, muttering about the deerly insane.
"…James, what is all this?" Remus asks when he and Sirius enter their dorm to find it covered in photos, parchment, and books. On the wall opposite James' bed is what Remus can only describe as a murder board.
"Personal project," James replies as he continues considering the murder board.
"Is Sirius Black the first?" Sirius asks, bewildered. James nods distractedly.
"Wait, you aren't the first?" Sirius shakes his head.
"I'm the third." Remus looks amused, "What?"
"Sirius Black the third, heir to the Ancient and Most Noble House of Black. Could you sound anymore regal?"
"Fuck off Moony." Remus laughs at him, "Prongs, seriously, what are you doing looking into my family?" James looks up.
"I am so glad you asked."
"Here we go," Remus comments as they sit on James' bed whilst he gets up to indicate at the board.
"Your family are all high achievers," James begins, Sirius crosses his arms and scowls, "Including you. They are all powerful, feared, revered, and respected. All but one." He pulls a piece of parchment off a photo in the centre of the board, revealing Andromeda. Remus bursts out laughing as Sirius' face twitches.
"ARE YOU REALLY STILL GOING ON ABOUT THIS?! THAT CONVERSATION WAS A WEEK AGO!"
"WELL IT TOOK ME TIME TO GATHER EVIDENCE!"
"WHAT EVIDENCE? THAT MY COUSIN IS A MUGGLE-BORN PRETENDING TO BE A PUREBLOOD?"
"DON'T BE RIDICULOUS PADFOOT! ANDROMEDA IS NOT A MUGGLE-BORN. THE EVDENCE CLEARLY SHOWS SHE'S A STRAIGHT UP MUGGLE! SHE'S IN KAHOOTS WITH THE SORTING HAT TO INFILTRATE HOGWARTS!" Sirius blinks at James, Remus falls off the bed laughing.
"WHY THE EVER-LIVING BANANA BREAD WOULD A MUGGLE BE INFILTRATING HOGWARTS?!" Sirius screams at his friend.
"I SHOULD THINK THAT'S RATHER OBVIOUS, YOU DOLT!"
"DOLT? ARE YOU KIDDING ME?!"
"NO. I'M SIRIUS." Sirius glares at James, "Look at the board Padfoot. The muggles know we are here! They know wizards exist and are biding their time until we aren't so against their presence before they wipe us out. That's why she's so gun-ho about muggle-borns and such." Sirius storms out of the room.
"I think it might be time to let this joke go, as much as I admire your dedication to it," Remus tells James as he wipes tears from his eyes, James frowns at his board.
"You might be right."
He really meant that, he did. But unfortunately, however much everyone might have wished otherwise, it didn't end there…
"Any questions?" McGonagall asks, James raises his hand, "Yes, Mr Potter?"
"The sorting hat. Would you say that's your domain or Professor Flitwick's?" James asks, McGonagall seems confused.
"It's an enchantment, a charm, however I do not think Professor Flitwick has looked into the Hat very much."
"But you have?" McGonagall nods.
"It was owned by Godric Gryffindor. I made it my business many years ago to investigate all things Gryffindor. Is this at all relevant to your work?" James shakes his head.
"No, just a side project I'm working on. Out of curiosity, have you ever heard of it having a special relationship with a student in particular?" McGonagall looks surprised.
"Only Mr Lupin." The class turns to look at Remus, only to find him asleep at his desk. The full was only two days ago, McGonagall had been content to let him sleep, she'd seen Sirius taking notes for him, so she knew he wouldn't miss anything.
"Um, Moons?" Sirius asks, nudging him awake gently, Remus whimpers slightly before blinking his eyes open. As soon as he sees where he is he sits up straight, blushing and looking at McGonagall apologetically.
"Sorry Professor."
"What's so special about your relationship with the Sorting Hat?" James asks Remus who looks at him in confusion.
"What?"
"You and the sorting hat." Remus blinks then clears his throat.
"Um, nothing? We chat sometimes. We had to do that biography focusing around strong magic users two years ago. I chose Godric Gryffindor, remember?" James nods, "I figured no one would know him like the hat, so I went to ask it questions and now I just go and talk to it sometimes. It gets lonely, likes having a chat with someone other than the Headmaster."
"It ever mention Andromeda Black?" James questions.
"ARE YOU KIDDING ME?! YOU'RE STILL GOING ON ABOUT THIS?!" Sirius yells, James flinches.
"I thought we decided that you were going to let this go," Remus reminds him.
"Yes, we did, but then something occurred to me. See I found school records of the Blacks going back generations. All of them were nearly straight O students, like Sirius. But not her, she gets mediocre grades at best," James tells them.
"SHE'S NOT A BLASTED MUGGLE!"
"Oh, that's what you're talking about," Peter says, Remus buries his face in his hands.
"James, if there were a Muggle in the school, don't you think someone would have noticed?" He asks, James grins.
"Someone did. See, the school records. She does fine in the theory, but her grades torpedo in the practical. Or they did, until she started partnering up with Ted Tonks. And it makes sense, doesn't it? He is a Muggle-born. He's on board with the plan for his parents' sake so he's trying to keep her from getting caught!"
"James this stopped being funny a month ago," Sirius tells him.
"I'm not kidding around anymore!" James insists, pulling a large binder out of his bag, followed by another, and another, "EVIDENCE!"
"James-"
"THE TRUTH IS OUT THERE MOONY, AND I'M GOING TO FIND IT!"
"The truth is out there, good line," some kid named Chris says in the back of the class, everyone ignores him.
"That hat has mentioned her," Remus tells them, everyone looks to him in surprise, "As an example."
"Of what?" Sirius asks.
"What being a part of each house really means. It's a list of traits, but how those traits are shown in each person is up to them. Slytherins are ambitious, some become power hungry, Andromeda uses that ambition to help people." Everyone seems thoughtful, "Or, as another example. Gryffindors value bravery, daring, nerve, and chivalry. Daring means adventurous or audaciously bold. Stereotypically of Gryffindors, this would equate to rushing headlong into danger or battling dragons or such. For some though, it means ignoring every warning sign and investigating your best friend's cousin, though it may cost him said friends' trust," Remus tells them, looking at James who seems sheepish. He puts the binders back in his bag.
"I'm sorry Padfoot." Sirius nods though he seems unhappy.
"Just, leave my cousin alone, all right mate?" James nods.
But it was not to be.
"…Potter, why are you reading a book about the Muggle political climate?" Lily asks as she walks into the common room, everyone looks over to James in confusion, he looks up guiltily.
"Um…"
"Prongs?" Sirius asks, "Why do you look like a stag in headlights?"
"The saying is a dear in headlights," Lily corrects.
"Yes, but he's male, so if he were a deer he's be a stag. I'm just being specific, now back to the important things," Sirius tells her dismissively, she rolls her eyes.
"I was just…" James trails off.
"Just what?" Remus asks suspiciously, James sighs, deflating.
"Looking for any indication that they know about us and might be trying to infiltrate Hogwarts." Sirius blinks at him, then calmly rises and walks into the dormitory.
"I hope you're damned happy with yourself," Remus snaps at him before following Sirius up.
"Six months," Lily tells James who looks to the ground, "This has gone on long enough. Come with me." James follows her.
Lily leads them down to the Slytherin Common Room where she bashes on the wall until it opens.
"What do you want, mudblood?" Barty Jr spits at her, James moves to pull his wand out, but Lily stills his hand.
"Get Andromeda out here." Barty Jr raises an unimpressed eyebrow, "Either get her out here or I will force my way past you and your precious common room will be tainted by the presence of a mudblood, so get a move on." Crouch goes.
"That was badarse!" James tells Lily who smirks, then remembers her anger at him as Andromeda comes out.
"Evans, Potter," She greets, confusion clear on her face.
"Would you please do magic?" Lily requests.
"What?"
"Any kind of magic, any spell, just perform something." Andromeda flushes slightly.
"I erm, I can't."
"Y-what?" Lily asks, James leaning back against a wall, arms crossed, looking smug.
"I lost my wand."
"Don't say it, Potter," Lily tells him.
"She lost her wand," James says, air quotation marks and all.
"Potter…"
"No witch does that. But Muggles lose useless sticks all the time, don't they?" He asks Lily who glowers at him.
"…What's going on?" Andromeda asks.
"Would you please just confirm to us that you can do magic?"
"How could I have reached seventh year at Hogwarts without doing magic?" Andromeda replies.
"Just what a muggle would say," James replies, and Lily goes to tell him to shut up but…doesn't.
"Thank you for your time, Miss Black." Lily turns, grabs James' arm, and hauls him away.
"And?" Mary MacDonald asks when the two get back to the common room.
"…He might be on to something," Lily answers.
"YES!"
"Lily, no!" Mary tells her.
"Look the way she said-"
"I don't care what she said, she's not a Muggle! You were supposed to be convincing him of that, not letting him convince you!"
Lily sheepishly looks to the ground.
Andromeda runs away from home after graduating. James uses this as further proof and causes a massive fight between the Marauders that doesn't end until Sirius almost kills Severus.
After Sirius runs away from Grimmauld Place, both Lily and James decide that, Muggle or not, it's for the best if they drop the subject of Andromeda all together. However, in the course of all their research, the two had found love. Sirius doesn't think it was worth it. He says so in his best man speech which he also uses as a chance to debunk their entire theory.
The case opens up again when the two go into hiding and have nothing better to do.
Then they die, and it's all but forgotten.
Fourteen years later, the Order is fighting Voldemort again.
"All the Blacks flaunted their magic whenever possible, Sirius, not just you," Remus clarifies to his friend who still seems putout at Remus telling Sirius not to show-off.
"They do?" Tonks asks, Remus nods.
"Why?"
"Well, I've just never seen my Mum do magic," she explains, Remus frowns.
"Really?" Tonks shakes her head.
"Now that I think of it, I've never even seen her with a wand." Sirius blinks at her, Remus looks to be considering something.
"Don't you dare, he already dragged Lily down that rabbit hole, don't fall down too!"
"I'm not, I'm not. I just think that-" Remus begins.
"Oh, for Merlin's sake, Tonks, would you please get your Mother here so we can finally bloody end this blasted conspiracy that some wacko came up with in 1975!" Sirius requests fiercely, Tonks seems confused but heads to the floo.
"Some wacko?" Remus repeats disapprovingly.
"I swear he didn't sleep for over a year trying to prove this utter horseshit theory of his."
"That language is not acceptable around the children Sirius," Molly reminds him. He opens his mouth to respond when they hear the floo, Sirius gets up, meeting Andromeda in the doorway.
"Andy, would you please do some magic of some kind literally anything please?" Andromeda blinks at him.
"I find out you're actually innocent, come over to see you, only to hear you still going on about James Potter's insane Muggle Conspiracy Theory?!" She asks him, sounding outraged. Sirius seems sheepish, opening his mouth to apologise when Remus chimes in.
"Or is she just trying to distract you, make you the bad guy?" Andromeda looks at him in annoyance before smiling.
"Remy!"
"Hi Andy, how are you?" Remus asks, moving to hug her.
"I'm good. Merlin, I haven't seen you since…oh, must have been Alice and Frank's wedding!" Remus nods.
"Wow, yeah."
"Been arrested lately?" Remus huffs.
"That only happened…" Remus trails off when the count goes above five.
"I love this so much," Ginny Weasley says from the background.
"CAN WE FOCUS?!" Sirius yells, looking completely mad. Andromeda sighs.
"I am not a Muggle, Sirius." Sirius nods, "But James was right, I can't do magic." Sirius' jaw drops, "My wand, it's core works best with the Dark Arts. Because of that I refused to use it when I was younger. I couldn't tell my parents, they would have flipped, so I tried to pretend everything was fine, but I haven't touched my wand since the day I looked into it's core. I didn't want to be them." Sirius stares at her in silence before stalking out of the room. Remus drops to the ground laughing because James was right, the bloody bastard was right!
"Sirius, where are you going?" Tonks calls, sounding nervous.
"TO PISS ON JAMES' BLOODY GRAVE!"
Remus doesn't stop laughing for a long time.
"Just because something is known for being good with the Dark Arts, doesn't mean that's all there is," Sirius tells Andromeda one day when she's visiting.
It soon becomes common place to find Sirius instructing Andromeda on simple spells as she timidly uses her wand.
Ted, Remus, and Tonks take over when Sirius dies.
After the battle of Hogwarts, Andromeda doesn't expect to ever pick up her wand again. Then she sees Harry levitating things around Teddy's head to make him laugh and she decides it's time to put that Slytherin ambition to good use.
"Can you teach me to do that?" Harry smiles at her and nods.
James, Lily, Remus, Tonks, Sirius, and Regulus Black all watch on as Andromeda learns more and more.
"So, no Muggle Conspiracy after all," James admits. Sirius smirks.
"No, but the truth was out there, and we found it." Remus chuckles.
"Did any of you see what Chris did with that line?" Everyone shakes their heads, "Come on, Hermione's binge-watching the series now, we can watch it with her."
"Oh, so that's why you keep such a close watch over Granger," Lily says teasingly, "You just want her television." Remus chuckles and nods.
"The truth is out there."