Authors Note – J K Rowling owns all characters you recognize. Any you don't recognize are of my own invention.
I have an idea of doing a series of stories around this premise, however it's not all thought out, so it might not happen.
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December 1981
The Death Eaters who had tortured the Longbottoms had finally been caught; they were in Azkaban sentenced almost immediately to life imprisonment. Auror's were now being sent to search each of their houses. When they arrive at the Lestrange house they are shocked to find more than house elves in residence.
Auror Fredrick King and Auror Kingsley Shacklebolt entered the Lestrange home and were immediately met by a line of house elves, which wasn't unexpected given the status of the Lestrange's, it was a very old wizarding family with a large manor house. What was unexpected, was the toddler that stood on the stairs.
"I didn't know the Lestrange's had a daughter." Fredrick said to Kingsley.
"Neither did I, it's strange that they didn't mention her when they were apprehended" Kingsley stated.
Kingsley approached the girl. "Hello, what is your name?"
The girl just tilted her head and looked at him. There was a squeak from behind him and then one of the house elves spoke up. "She has no name; she is just called 'The Child'".
"No name, but this girl must be over a year old?" Kingsley questioned.
The house elf cowered slightly at the tone of Kingsley's voice. "Yes sir, she's almost 17 months old, but the master and mistress just call her 'the child'." The elf then added, "When they talk about her at all." The elf then hit himself in the head repeatedly. "Bad elf, bad bad Finchy" he said to himself.
Kingsley turned back to the girl. "Hello, I'm Kingsley. Are you alright?"
The girl nodded, but remained completely silent.
Another squeak and a different elf stepped forward. "The little miss doesn't speak yet."
Kingsley didn't have much experience with children, but he thought that kids could normally speak at least a few words by the time they were the age of the girl. He knew little Neville Longbottom was around that age and could form some sentences.
"Fredrick, I think we should take the girl back to the Ministry now, and then come back later to go through the house"
"I agree." He then turned to the house elves. "Would someone pack a bag of the child's things?"
The elf, Finchy, that had previously been beating himself in the head, bowed and said "Yes sir", then promptly disappeared. He reappeared in mere seconds with a small bag.
Fredrick took the bag; it contained a single dress a pair of tights, a jumper, a hair brush and a tooth brush. Before he could question the elf on the sparse contents the elf volunteered. "It's everything she has."
Fredrick frowned and cast a sad glance toward Kingsley and the girl.
Kingsley reached out to the girl. "Would you like to go on an adventure?"
The girl raised her arms to him unquestioningly. Before leaving Kingsley turned to the house elves. "We'll be back shortly. Thank you for looking after the girl in her parent's absence." The elves all bowed solemnly.
XXXXX
Once Fredrick and Kingsley arrived back at the ministry they separated, Fredrick went back to the Auror department to report what had occurred, and Kingsley went to the Department for the Welfare of Under-aged Wizards and Witches.
The department had lately added a number of new staff due to the number of orphaned witches and wizards that had resulted from the recent war. Kingsley was eventually led to the desk of a witch named Paulinda. Paulinda was at least 80 years old, she explained that she had retired almost 20 years earlier, but had been brought out of retirement following the war to help the department get a handle on things.
Kingsley put the girl down in one of the chairs across from the desk, and took the other for himself. He then explained finding the girl.
Paulinda pursed her lips and took a large tome down from a shelf next to her desk. She waved her wand over it while speaking "Bellatrix Lestrange nee Black". Opening the book she looked at the information provided to her. "Our records do not indicate that Mrs. Lestrange has a child."
"We in the Auror's office were not aware of it as well."
"Do we know for sure that she is the Lestrange's child?" Paulinda asked Kingsley.
"She was found in their home, seemingly being raised by the house elves. If she's not their child who else's would she be?"
Kingsley turned toward the child and considered her looks. She didn't necessarily look like Bellatrix or Rodolphus who both had dark hair, whereas the child before him had long snow white hair, but he was no expert in these things.
"Do you know your mother's name?" Paulinda asked the child.
"She doesn't speak." Kingsley said, but saw that the girl nodded in the affirmative.
"Doesn't speak? Strange, very strange. Is your mother's name Bellatrix Lestrange?" Paulinda asked.
Again the girl nodded in the affirmative.
"We can do a blood test later to confirm her parentage." Paulinda again glanced at the book she had consulted earlier. "It seems that the girl has two living aunts, a Narcissa Malfoy and an Andromeda Tonks. We will contact Mrs. Lestrange's solicitor to see if she has a preference as to which Aunt the girl is placed with."
Kingsley frowned. He knew Narcissa Malfoy's husband, Lucius. He had been implicated as a Death Eater, but so far nothing had been proven, and unless it was proven there would be nothing to keep the girl from being placed with them, and he was sure it would be with the Malfoy's that Bellatrix would want her daughter placed.
Paulinda thanked Kingsley for bringing in the girl, and he was told she'd see to the child from there.
Kingsley rose from his chair and looked down on the child. "Good bye little one. This nice witch is going to look after you now and find you a nice place to stay."
The girl looked up at him and as he started to turn away, she reached out and grabbed his hand and squeezed it. She nodded at him and released his hand just as quickly as she had grabbed it.
XXXXX
It took a few days to get things sorted. At first Bellatrix didn't even acknowledge that she had a daughter. Rodolphus did admit to the child, but wasn't sure when she was born, although he did indicate that the child should be sent to live with the Malfoy's. Finally Bellatrix snapped out of whatever crazy haze she was in, and indicated that "the child" was hers, she had done her duty in having a pure blood wizard child for her Dark Lord. The child had been born on 31 July 1980, and no, she hadn't been given a name, she was waiting for the Dark Lord to meet the child and bless her with a name. As she had been off working for him she had barely seen the child.
A week after first meeting "the child", Paulinda walked up the path to the impressive Malfoy Manor. She was let in by a house elf who took her to a sitting room and then went to fetch his masters.
When the Malfoy's entered Paulinda rose from her seat to address them, the made an impressive couple.
Lucius Malfoy looked down his nose at Paulinda.
"Hello." She greeted them. "My name is Paulinda Lewett, with the Departmant for the Welfare of Under-aged Witches and Wizards. I'm here to talk to you about Lady Malfoy's niece..."
Narcissa interrupted, "My niece? I don't have a niece, unless you're talking about the child Andromeda had with that … mud… muggle."
"Um, yes, well…" Paulinda stammered, "Actually I was referring to the child of your sister Bellatrix and her husband Rodolphus."
"Bella's daughter? Bella doesn't have a daughter."
Paulinda reached into her attaché case and pulled out a piece of parchment. "Yes, well it seems that not many knew about her. I have a signed statement here from your sister saying that the child was born on 31st July 1980. She asks that custody of her daughter be given to you and your husband."
Lucius Malfoy who had been quiet thus far, took the parchment from Paulinda and looked it over "The child is almost a year and a half old, where has she been?"
"The best we can tell is that she's never left the Lestrange home. She was found about a week after the Lestrange's were arrested, it seems that the house elves were taking care of her."
"What is her name?" Narcissa asked.
"The child wasn't given one. According your sister's statement, she was waiting for he who shall not be named to 'bless' the child with a name. Will you take custody of the child? If not, we do have a number of families who would be interested in fostering and possibly adopting the child."
Narcissa turned to Lucius, but before she could even say anything he said forcefully, "No pure blood niece of mine will be raised by who knows what kind of family."
"Yes, well, um, very good then, it is obviously our preference to put children with blood relations, and of course there is her other aunt, but your sister was quite adamant that the girl should go to you. We would like to proceed as quickly as possible in granting you guardianship. We could bring the child by tonight. We would need to do a few follow up visits to make sure the child is adjusting well to her new living situation."
Narcissa could tell that her husband was about to object at being checked up on by a department of the ministry, but Narcissa laid a hand on his arm to calm him.
He growled out "Yes of course" instead of arguing.
Narcissa added. "We are happy to take her as soon as possible. We have plenty of room, and we have a son around the same age, it will be fun for them both."
Paulinda made her move to leave. "I do want to mention one other thing. The girl does not seem to speak yet."
"Doesn't speak?" Lucius questioned harshly. "Is she a simpleton?"
Paulinda looked at him severely. "Not at all, in fact she seems quite bright for her age. We've had her checked out by a medi-witch and can find no reason for her lack of speech. It seems that perhaps she hasn't had much interaction with people to have had a need to talk. Her parents didn't seem to acknowledge her and the house elves just took care of her. I'm sure once she's integrated into a loving household she'll pick up on how to carry on a conversation. Now if you'll excuse me, I'll go prepare the proper paperwork and collect the child and bring her straight over. I ask that you think about the name you'd like to call the child, so we can adjust the paperwork accordingly."
XXXXXX
In less than two hours, Paulinda was once again approaching Malfoy Manor, this time with 'the child' on her hip. She was greeted in the entryway by the entire Malfoy household this time, including Draco, the son of Lucius and Narcissa, along with a large number of servants and house elves. Narcissa looked to her husband for permission and upon receiving his nod; she rushed forward, and put her arms out for 'the child'. To the surprise of all, the child, turned and gave Paulinda a hug, and then went readily into her Aunt's awaiting arms.
Lucius picked up his son and strode over to his wife.
"I'm your Aunt Cissy, and this is your Uncle Lucius and your cousin Draco."
The child looked at each of them and smiled a smile that could be described as "brilliant".
Paulinda took in the sight. They truly looked like a family, the girl with her long snow white hair and pale skin fit right in.
Lucius motioned one of the servants over. "Nanny Emeline, please take the children up to the nursery while we finalise the paperwork with Miss Lewett." He put Draco down and Narcissa handed the child over to the nanny.
"Miss Lewett, please follow me into the library so we can conclude our business."
Once in the library Paulinda pulled out a stack of parchment from her attaché case and placed it on a table in the middle of the large library. She then pulled out a bottle of ink and a quill and placed them beside the stack.
"Have you thought of a name for the child?"
Narcissa looked to her husband to answer for them. "She will be known as Neve Bella…" He then hesitated for a moment and continued, "…and we'd like her to take the Malfoy name".
Lucius was in no way ashamed of his ties to the Lestrange name, but it would make things easier on the child growing up if she was known as a Malfoy.
Paulinda was not surprised by the request, however she didn't think the request would happen so soon, she figured within a few years they'd put in the request. "Yes, of course, Neve Bella Malfoy, a beautiful name for a beautiful little girl. Mr. and Mrs. Lestrange have already signed away their parental rights, so we can take care of the name change and adoption without delay."
For the next half hour the Malfoy's and Paulinda went over the paperwork. Filling in the appropriate names and signatures as required.
After everything was signed and sealed, Paulina pulled out a small bag. "Neve, oh it's nice to have something to call her, Neve didn't have much when she came to us, just what was in this bag." Then pulling out another bag, she continued, "while she's been in our custody she has acquired a few other belongings, a few outfits and toys." She placed the bags down on the table.
Lucius sneered at the charity bag, knowing it would be incinerated at first chance, plus he knew his wife couldn't wait to start buying pretty dresses for the girl. After all, it was just a few days until Christmas.
Paulinda then pulled out a large old key. "We acquired this from the Lestrange household; it is the key to the Lestrange family vault at Gringotts."
Lucius took the key from Paulinda. "Thank you Miss Lewett. We appreciate your help in bringing our niece to us."
Paulinda smiled. "It is my pleasure sir. As I mentioned earlier, we will check in from time to time to make sure everything is going okay, but with your standing in the community, and the ministry, I don't see that we'll have any problems."
Paulinda was seen out, and Lucius and Narcissa headed up to the Nursery to get acquainted with their newest family member.