I have changed how long Dumbledore has been dead from 13 years to 6. Sorry for any confusion! I have gone back and changed it.
TW at end of chapter

Shit! Harriet thought to herself as the reality fo the situation hit her like a train. Both Lily and Harry were blocking the doorway, James the floo, making it impossible for her to flee.
"Look," Harriet started, swallowing the lump that had formed in her throat. "I don't want any trouble. I dunno why you're doing this and frankly I don't care. Just give me back my wand and let me leave." Her voice was much more forceful than her heart, which had begun to hammer so loudly in her chest that Harriet was half convinced everyone could hear it.
"Kiddo-" James started to say from behind her before Harriet whirled around violently to face him.
"Don't call me that!"
James raised his hands in surrender again before taking a step closer to her. Harriet wished he wouldn't. "I honestly don't know what has happened, but I can guarantee that it's not what you think. Why don't we all sit down so we explain things. Calmly."
Harriet was half tempted to give another Fuck you but thought better of it when she realised she would be going against three adult wizards without a wand. That didn't mean she would cooperate fully with them. She just had to pretend
"Okay."
James' shoulders slumped slightly as he, Lily, and Harry went to sit down on the couch, leaving the armchair for her. Harriet huffed a short, tense breath before carefully sitting on the edge of the seat.
"Why do you think we're working for He-Who-Must-Not-Be-Named, dear?" Lily's voice was as soft and comforting as ever but it didn't have the same effects on Harriet. Instead, she felt the strange urge to throw a nasty hex at her. Or a chair, seeing as her wand was still clenched tightly in Harry's hand.
"You know exactly why."
Harry huffed at that, rolling his eyes exaggeratedly. "How are we meant to have a peaceful conversation with you when you won't even cooperate?"
"Harry-" James started warningly, but it was too late. Harriet felt that familiar fury curled inside her gut like a sleeping dragon awaken, its fire spreading quickly throughout her entire body.
"Cooperate? Why on earth would I do such a thing when it's clear that you've tricked me!" As each Potter went to open their mouth with a retort, Harriet pushed on. "NO! You can't even deny it when you've been hiding a diary from Voldemort! Why would you hide such a thing if you weren't working for him?" By this point, Harriet had stood up and was pointing at each one of them as though her fingers were daggers. "So, really, I don't see any reason why I should 'cooperate' with you!"
James frowned before carefully looking at Harriet. "Harriet," he said slowly, "we don't know what book you're talking about. We've never heard of such thing."
Harriet scoffed, opening her mouth to give another round of insults, but stopped abruptly when she saw Harry's pale, sickly face. "Can you show me this diary, please?" He said slowly, carefully.
"No! Do you think I'm stupid?"
"Please."
Eyes scanning Harry furiously, Harriet frowned. Really, she didn't need the book. It was more the principal of the matter. On the other hand, if giving the book gave Harriet enough time to run, she supposed she could agree. "Only if you give me my wand back."
Harry's eyes narrowed with cold assessment. "Only if you promise not run."
"And why would I promise such a thing? For all I know, you're Deatheaters."
"I'll give it to you after I've explained."
"So there is something to explain."
Harry exasperatedly pinched the bridge of his nose, closing his eyes tightly as if to fight off an approaching headache. "Just, tell me, is it small and black? Handwritten?"
"Yes."
Harry nodded once. "Mum and Dad don't know about the book at all. I hid it there myself."
"Harry!" Both Lily and James scolded.
"But with good reason!" Harry said quickly. "It was right before Dumbledore went to fight He-Who-Must-Not-Be-Named for the final time. He asked me to keep it safe. Said that there was dangerous information in it that couldn't get into the wrong hands."
Harriet snorted a sarcastic "I'll say" as James turned to look Harry directly in the eyes. "What information?"
Harry seemed to hesitate for a second, shifting in his chair slightly before clearing his throat. "Well, you know how Voldemort had that Horcrux? The Diary?"
"Yes," both Lily and James chorused slowly.
"It was notes by him on how he created it."
"So let me get this straight," Harriet interrupted. "Dumbledore gave it to you right before he died to keep safe and you put it at the back of a bookcase?"
Harry opened his mouth then closed it again with a frown. "Hidden in plain sight?"
James snorted.
"How am I supposed to believe you? You guys could have created this whole thing to get information from me!"
"What information?" Harry asked.
Harriet's eyes widened as she pointed at Harry. "See?"
James huffed. "How else could you explain how we look so much like your parents?"
"Polyjuice."
"And where would we have gotten the hair? The fingernails?"
Harriet opened her mouth and, much like Harry, closed it again. "Well, maybe you're using a really complicated glamour?"
"I think you know logically that there's no glamour that can be used to make a person resemble someone else so greatly." Lily objected quietly.
Harriet huffed, pinching the bridge of her nose harshly as if it would help her find more reasons not to trust them. When she couldn't, her shoulders hunched downwards. Was it really possible that they were telling the truth?
The reality of the situation crashed upon Harriet's shoulders like a house. Oh merlin! She had just attacked her fa- James! And accused them of working for Voldemort of all people! "I-I'm sorry!"
Each Potter's face softened exponentially. "Its okay," Lily reassured, making Harriet feel even worse for how she acted.
Harry snorted, covering his mouth to disguise it as a cough. "It's really okay, Har. Besides, it was rather funny seeing Dad have to dodge like that. He looked like a niffler trying to steal from the goblins!"
Lily covered her mouth as a giggle bubbled out, James turning to glare at the two before slowly allowing himself to smile. Harriet found it in herself to give a hesitant chuckle, even if it was just to humour them.
The moment was sobered by James' next question. "Why was your immediate reaction to believe we were Deatheaters?"
Harriet's grin melted from her face as she turned her face downwards to look at the rug. "It's nothing against you guys and all. I suppose the resurrection of Voldemort has got me a bit on edge is all."
"I'm sorry, what?" Harry exclaimed, jumping off the couch so quickly that Harriet couldn't help but flinch. She really should start assuming that nothing that happened in her world happened in theirs.
"I-is Voldemort not in power here?"
"Honey," Lily started, "Voldemort was defeated by Albus Dumbledore over six years ago."
"It's how he died," James added quietly, a flash of sorrow glinting from his eyes before he could mask it.
"Oh," was the only thing Harriet managed to choke out, suddenly feeling rather faint. The world tilted slightly as she slumped against the back if her chair. "S-so he never killed the two of you?And then he was defeated Dumbledore?"
Logically, she knew that she shouldn't feel sorrow cracking through her heart. Logically, she knew it was no one's fault but her own that her parents died. Logically, Harriet even knew that no one could have saved her from meeting Voldemort time and time again with little to no help from the adults around her. It was just the way it was.
That didn't seem to make it hurt less.
"Did you ever meet Voldemort?" Harriet asked Harry carefully. Maybe he had had to face some of the things she had. Maybe she wasn't alone in all that she faced. Maybe-
"No," Harry said quietly. "Well, I saw him during the final battle, helped keep him distracted before Dumbledore could reach him."
"And even then you shouldn't have had to face him," James frowned disapprovingly.
"I was an adult!"
"Barely," Lily argued.
"Oh," was all Harriet managed to say.
"Why are you here, Harry?" James asked suddenly as a newfound stillness settled over the occupants of the house.
Harry winced slightly. "It appears I inherited your cooking skills. I left pasta on the stove without enough water. Nearly burnt down the whole apartment."
Lily sighed in exasperation, looking fondly down at her son. "Harry was in a right state when I arrived to help him put out the fire. We decided after assessing the damage that it would be better for Harry to come stay here while they repair the place."
"Ginny decided to go visit her parents for a while. That's why she's not with me."
"Ginny?" Harriet asked with a small frown. This was the second time Harry had mentioned her.
"Yeah, my girlfriend."
Harriet's eyes bugged out of her head slightly as she stared at Harry in a newfound light. She couldn't imagine dating Ginny; she was like a sister to her.
Harry merely chuckled at her expression, seemingly reading her thoughts.
Silence descended upon the room, pink and golden hues from the last rays of sunlight tinting the room an odd glow. It was peaceful here, Harriet realised with a start, as she looked around the room. Besides the obvious fact that there was no more Voldemort, no more Deatheaters to ruin people's lives, there was also a tranquility that she had never had at Private Drive. On occasion she had felt it at the Burrow and Hogwarts, but mostly she had been too busy to be able to sit quietly for more than a minute at a time. A bird sung in the distance; a melancholic melody that made Harriet realise that she had never heard her mum sing. She didn't even know if her mum ever did sing.
Despite being surrounded by faces of her parents, of a brother she could have had, Harriet couldn't forget that they weren't hers. And that made her feel more alone than ever.

The rest of the week passed quickly and despite Harriet's best efforts not to, she had slowly started acclimating to the Potters' home. Harriet was always the first to wake up in the mornings, giving her time to study Riddle's book without the scrutiny of others. When she heard the light footsteps of Lily or James waking up, she would quickly go downstairs and help them cook breakfast.
Harry and James both appeared to be keeping quite busy at work but Harriet could never hear what about, their voices hushed and private. Harriet couldn't tell whether Lily simply wanted to keep her company or was worried about her running off, as despite the two jobs Lily clearly had, she spent each day with Harriet. It wan't bad, per se, but Harriet wasn't used to having an adult's attention all to herself for hours on end. For the most part, Lily left her to do what she pleased, allowing Harriet to study as much as she could about this new world she found herself in.
Mcgonagall had taken over as Headmistress after Dumbledore died. Severus Snape was never a potions professor and, instead, some bloke named Slughorn took his position. The Minister was not Fudge, had never been Fudge. Instead, a kind looking man named Kingsley Shacklebolt took that position. When Harriet had brought it up at the dinner table one evening, James had smiled, exclaiming he was the good Minister but an even better person.
On Wednesday, Lily had finally drug her out shopping, despite Harriet's protests that Harry's old clothes worked perfectly fine. It had taken the whole day due to Harriet's protests at the purchasing of each new item of clothing and Lily's insistence that she needed more. Remus had told her stories about Lily's great persistence in third year, but to see it in person was an entirely different experience. By the time they had gotten home, Harriet had more clothes than she ever had before.
Lily refused to hear her gratitude after the fifth time she tried to express it.
Harriet still hadn't heard anything about getting her back to her own world, and every time she went to bring it up, all the air seemed to leave her lungs. (She wasn't really sure what that was about.)
The only hitch in her days had been the amount of food that both Lily, James, and Harry had pushed upon her. After a month at the Dursleys, Harriet wasn't used to having one proper meal a day, much less three. Her eating habits had never been a problem before, as Mrs Weasley had always been preoccupied with keeping Fred and George from doing something foolish while also ensuring that Percy ate in between his paperwork, leaving Harriet to eat in peace. Here, however, Harriet could tell that the Potters noticed her odd eating habits, making it harder to slip by unnoticed. They hadn't brought anything up, but the frowns on their faces told Harriet that it was only a matter of time.
"Can you pass the Ketchup?" Harry asked Friday evening as they all sat down, after James' insistence, for a burger dinner.
Harriet was astounded that he was still eating, having already devoured the entire burger. Harriet herself still had well over half her burger and chips and could already feel her stomach gurgle unhappily at the amount she had eaten. Still, Harriet had rather feel a bit poorly than have Harry's stare pierce her soul.
"What did you guys get up to today?" Lily asked as she passed Harry the condiment.
"Oh, you know, the usual," Harry replied before shoving a handful of chips in his mouth.
James sighed. "Slow down, Harry. Nobody's going to take that from you."
Harriet swallowed uncomfortably at that comment, her food turning to ash in her mouth. Her stomach gave another painful lurch as her hands trembled slightly. She wasn't sure if it was from anxiety or the aftermath of the cruciartus curse she had been held under almost three months ago.
"Anyways," James continued. "Had a lot of paperwork today. Nothing special."
The quiet breaths and swallows of food were the only break in silence.
Suddenly, Harry perked up. "Hey, Harriet?"
"Yes?"
"Y'know how you said that your defence professor was possessed by You-Know-Who?"
Harriet did not like this line of questioning. Not one bit. "Yes?"
"Well," he continued, oblivious to her discomfort. "I was wondering if you ever saw him?"
By now, both James and Lily had stopped their quiet chatter, looking intently between the two.
"Erm, well, yes?"
"Really? What did he look like?"
"Well, what did yours look like?"
"Eh," he shrugged. "He looked sorta waxy, distorted. His eyes were red which was bloody creepy."
"Oh," Harriet remarked processing the statement. "Mine didn't look like yours. He kinda looked like a snake. Didn't really have a nose."
"Really?" Harry asked excitedly, leaning forward.
"Erm, yeah. I suppose it was worse in fourth year than in first." She replied distractedly, caught in the tsunami of memories that had threatened to overtake her reality.
Quietly, almost as serious as he had been when she was firing stunners at him, James asked "How many times have you seen him, Harriet."
Blinking slowly, Harriet realised her mistake, looking down sheepishly as she tried to gather her thoughts enough to give an answer that would satisfy them. "Well, I suppose I saw him three- no, technically four times?"
Lily gasped quietly. "How-"
"You know, I'm rather tired," Harriet rushed out. "I think I'm going to head to bed. Er, thanks for the food." And with that, Harriet leapt out of her chair and dashed towards the reprieve of her room.

Admittedly, Harry felt horrible about tricking Harriet into answering more questions. But it had been a week now, and she hadn't volunteered any explanations, any thoughts on why she may be here. Harry knew that his dad had argued with Moody days ago about letting her get settled in before asking her more questions. Moody had simply argued that they didn't have time, especially with the increase in wizarding terrorist attacks across the country. They had kept all of them out of the papers so far, but it was only a matter of time before the public found out.
Harry also knew that, despite his dad's best efforts to keep his feelings towards Harriet strictly working-professional, he had developed a fondness for her. Almost like a daughter.
Really, Harry wasn't surprised. He had caught his mum on more than one occasion acting overly motherly towards her and he was already seeing her as a little sister.
Harry had only wanted to help his dad who was already overwhelmed with finding the mass attackers. He wanted to help his dad who already had too much guilt.
He just wish it hadn't upset Harriet so much.

Carefully, the small, hunched figure carried the golden ring towards the pile of rags that lay on the dusty, moth-eaten chair. The room around them was dark, the only source of light the full moon that filtered through the small crack in the roof, casting eery, living shadows on the dilapidated walls.
"M-master," the small man said, his rat-like features even more prevalent in the low lighting. "I-I have brought you the stone."
From under the chair- no, within the rags on the chair, a dry voice that sounded more like nails on a chalkboard, spoke. "Bring it to me."
"Y-yes M-Master," the man complied, practically tripping over his oversized feet in haste to comply. As soon as he rested the ring within the folds of the cloth, however, he leapt back, as if afraid of being burnt.
"Ssseverus," the voice hissed, sounding stronger, surer. "The potion. Bring it to meeeee."
Slowly, the shadows in the far corner of the small room unfurled, catlike, moving slowly upwards until it took the shape of a man. His pale face was almost translucent in the light; long shadows making his already hooked nose more pronounced. Unlike the first man, Severus walked calmly, with measure, over to the rags. With flourish, he retrieved a small bottle from a pocket by his chest, uncorking it with a small pop before unceremoniously pouring it on the chair.
A sharp hissing noice burst forth, gaining intensity until the whole room seemed to be filled with it. Black steam furled upwards like coiled snakes; ready to strike at any moment. Suddenly, the rags shifted, lurching upwards with such force that the smaller man squeaked. Severus turned to glare sharply at him before spinning back.
The rags had started to expand now, a frothing, spitting potion whirling violently in place before falling away to reveal a violently red ball in the centre. If Severus cared to look, he would have been able to recognise the shape to actually be like a baby's; grossly elongated limbs and skin raw, blistered, and oozing with welts.
Severus did not care to look.
Just like the rags, the figure began to bubble, slowly growing, changing, until his skin began to knit itself back together, going from the violent fuchsia to a pale olive tone. The baby-like body slowly grew until it reflected a young man's.
Slowly, he stood, eyes opening to reveal ruby red eyes and a face so young and handsome Severus had a hard time believing that he had just come from that. Quickly, he kneeled, offering dark robes and a skeletal white wand.
The man quickly took it before giving Severus a cold, cruel grin, trademark of only one person.
Tom Marvelo Riddle was back.

I am soooo excited for the next chapter! The story's really going to start picking up its pace!
Have a lovely day and thanks for reading!

TW eating problems, allusions to abuse, slight panic attack.