A/N changed a few things in the prologue. Nothing major, I don't think (I have really bad memory and I did it a day or two ago) just a few details like the note he came with. 

"COME ON BOYS, WE'RE LEAVING!" The Weasleys scrambled around the house grabbing bags and putting on shoes. Nico and Ginny were the only ones ready, standing by the fireplace. "COME ON, WE DON'T HAVE ALL DAY. PUT THAT DOWN RON. NO FRED, YOU CAN'T BRING THAT!" Mrs.Weasley yelled, running around as she attempted to herd everyone to the fireplace.

Today they were going to Diagon Alley to buy supplies for Hogwarts. It was scary for Nico because next week he would board a train and go to some castle boarding school for a whole year. It was also especially nerve wracking because today Nico would finally open up the bank in Gringotts that his family had left him. He kept on repeating the number of the vault in his head, 1000. A fairly easy number to remember, but when he had told his parents that that was the number on the note he was left with, they'd looked at him strangely. Now, Nico wasn't dumb. He knew this probably meant I don't think there is a vault number 1000 but since his parents said nothing, he decided to have faith in it.

A loud bang interrupted him from his thought, and Nico looked up to see that Mum was still struggling to get everyone ready. Nico thought the chaos quite amusing. Ginny, obviously, did not. "Come on, all you have to do is put your shoes on and grab your wands. Hurry up!" she whined. Ginny was still upset at the fact that she was the only one not going to Hogwarts this year. Nico felt a little pang of sympathy at being left behind, but to be honest he'd never had the best relationship with his sister. It just always felt like she was trying to replace someone.... When he thought about the word sister, two people appeared in his mind, along with a strange pang of loss and grief. Neither of the people were Ginny. But as soon as he'd try to focus on their face or anything about them, they just got blurry and he'd lose his train of thought.

Nico shook his head, as if he had water stuck in his ears, and frowned.

Ten minutes later, everyone was finally ready and were taking turns stepping into the fireplace and saying "Diagon Alley"

Nico hated Floo Powder. He felt sick and dizzy afterward, and it just felt..wrong. He was- Nico's thoughts went blurry and shook his head to get the sensation out. It seems to happen to him a lot.

Ron, Fred, George, and Ginny ran ahead to who knows where, and Nico trailed behind them. He always felt like this. An extra wheel. An outcast. The 8th who shouldn't be there. Nico frowned, why do I have a strange sense of deja vu when I think of that? Whatever. Nico is and would always be the outcast. He may join in on the twins' antics, or listen as Ginny rants about boys she likes-notably, the notorious 'Harry Potter'-, or play quidditch with Ron, he still didn't feel that close to them. A little while ago however, when Nico was still in the closet, Ron was the first he'd come out to, and that had helped them become a little closer.

But, he remained the outlier. Not only was he not a Weasley by blood, he looked starkly different. The Weasleys all had red hair and skin that freckled in the sun, Nico had raven black hair and pale skin that burned to a crisp if he was out in the sun for too long. Nico was scrawny, with high cheekbones that cast shadows on his fair skin, and always had bags under his eyes. No matter how much Mum tried to fatten him up, "It looks like we've barely been feeding you!" she'd said, it made no difference. He guessed he just had a high metabolism.

As he got closer to the Gringotts, a wave of anxiety that made his stomach clench reminded him of another thing that made him different from the other Weasleys. He had always been relatively quiet. Social interactions made him nervous, and he generally avoided talking to people he didn't know. And now, he was about to go into a bank, give a goblin a number key, and a note to open a bank vault he wasn't even sure existed. His hands were slightly sweaty and it felt like the shadows he walked past were brushing against his ankles. Nico started playing with his skull ring, a nervous twitch he'd had since forever.
Nico shivered. He felt a hand on his shoulder "You'll do fine Nico, just go up, give them the key, and state your vault number. I'll be right beside you the whole time." Nico looked up at his dad who smiled at him reassuringly. Nico gave him a meek smile in return and together they walked up the steps to Gringotts bank together.

•~•~•

Inside there was a large chandelier hanging over marble floors. There was a large u-shape of countless numbers of goblins at reception desks, scribbling on papers. Nico walked up to a goblin and coughed. Ignored. He coughed louder.

"Can I help you with something?" The goblin asked lazily without even looking up.

"'I'm here to open vault number 1000, here's the key," Nico said, handing him the 'identification' key and the note in his bag he'd come with. When Nico mentioned the number of the vault, the goblin visibly perked up and snatched the note from Nico. The note was strange. It had had his vault number and key attached. But at the bottom there were some strange symbols that looked like gibberish. Apparently not to the goblin though because, when he read it, his eyes widened and they looked as if they would pop out of their sockets- and he looked momentarily terrified. "Y-your N-ni-co di Angelo, sir. I apologize for my rudeness sir. I was unaware of your identity. P-please for-forgive me." he stuttered.

Nico looked back at his dad with a confused expression. "What the bloody hell is going on with this guy?" Nico mouthed at him. He shrugged, looking as lost as Nico felt.

"Yep, that's me. Nico di Angelo." he said, rolling my shoulders. If there was anything Nico was good at, it was pretending to be someone he's not. "Now lead the way"

•~•~•

The mine cart finally shuddered to a stop after a ride past a dragon, through a waterfall, and countless vaults and floors. He'd lost track of time somewhere around the two-minute mark of trying to count the seconds. What can he say, trying to stay focused on counting that long was difficult, especially in a jittering mine cart, underground, as they rode an underground death roller coaster.

Hazel would've loved it. Wait who was Hazel?

As soon as the thought appeared in his head, it slipped out like water running through his hands.

His thoughts wandered, but they kept coming back to one thing, My real last name is di Angelo, and apparently, my family must've had some influence over the goblins to warrant a reaction like that.

Nico shook his head and stepped out of the mine cart. The goblin led him down a confusing maze of stone passage ways until they finally came to a halt. Nico waited for them to continue, until he finally looked up from the ground (yes he'd been staring at the ground, he was nervous, OK?). Only then did he finally notice what he was standing in front of. A giant bubble of black, like the shadows had gathered and solidified to create a massive force field. Actually, that's exactly what it was. Wait, how was he so sure?

"What am I supposed to do now? How do I get to the vault?" Nico mused, kinda annoyed at this weird security measure. Of course if he was a weirdo, his biological family had to be too.
"Do I knock on it?" If anything, his mum had taught him that the polite thing to do was to knock before entering a private room. That's mostly because of a reason he'd rather not think about.

He moved forward, before his thoughts could get too carried away, and knocked on the bubble.

The goblin beside him gasped as the barrier dissolved into a dark cloudy mist: dancing shadows swirled around, some moved forward to gently caress him and wrap in spine-tingling tendrils around him, forming a sort of shadow-armor. After a moment the shadows uncoiled themselves from him, almost reluctantly (was it that just him?), and dissipated, scattering into the darkest corners they could find of the large cavern Nico found himself suddenly in.

Nico took in a sharp breath. He was standing in front of a massive, ornate door made of bronze, gold, and encrusted with more types of precious gems than he could name. On the door there were people carved, people with swords, people carrying shields and running into battles with monsters and other people. The carvings swirled and danced, and Nico felt like the more he tried to focus on a specific scene, the more it all seemed to swirl together into one big movement, pushing and pulling like waves. Back and forth, back and forth...

It was mesmerizing. It held stories, myths, legends, so many lives: all on this one door.

Who in the world am I related to? Nico asked himself for the gazillionth time, Am I royalty or something? Cause that goblin sure acted like I was... Nico's thoughts were interrupted by a growl.

Nico tore his gaze from the carvings and saw what was sitting in front of the vault door: a dog. Not any old normal dog though, this dog had beedy eyes the colour of blood that seemed to look right through him and into his soul. Which it probably did, Nico wouldn't have trouble believing that the comically over-sized black-mastiff was a supernatural being that could definitely see his soul. The gaze made him feel uncomfortable, and he unconsciously started twiddling with his ring.
Nico heard a cough beside him. "I regret to inform you, sir, that you are on your own from here. The note said you needed to open the vault on your own. It said you'll know what to do when the time comes." the goblin managed to say without stuttering, though he still spoke with a slight undertone of fear. Better than stuttering though, Nico thought to himself, Maybe he only just realized that I wouldn't fry him or whatever he expected me to do. "I'd best get going then, I'll wait in the mine cart." He said, then scuttled away.

Wait, what am I supposed to do, he can't just leave me here! Oh well, at least I told Dad that this would probably take awhile and that I'd meet up with them later at half past ten by the Leaky Cauldron. Nico thought with a scowl.

Nico hoped it wouldn't take that long but, knowing his sour luck, it'd probably take even longer.

•~•~•

Nico hesitantly took a step towards the massive dog, who couldn't seem to care less that Nico was there. Wait, scratch that, he looked excited. The massive dog jumped up and ran at Nico, knocking him down to the ground. Despite what his brain was telling him-which was something along the lines of 'ALERT! ALERT! MASSIVE, SUPERNATURAL DOG JUST POUNCED! DEATH IS IMMINENT!'- his body relaxed and he laughed an actual, genuine laugh- shocking. The dog started licking his face. It's tail was going crazy, thrashing back and forth ecstatically.

"Can I get up now?" He asked after a minute, trying to push the dog off of him. It did something that looked suspiciously like pouting and then let him get up.

Nico could feel the dog's eyes trained on him as he turned and walked towards the lavish door once more.

When he got there, he tried knocking again. Nothing. Well, it was worth a shot, better go back to that goblin and tell him that he had no clue how to open this thing and that he'd absolutely no idea what the goblin meant by "You'll know what to do when the time comes."

Nico spun around and had already started to make his way to the edge of the cavern, when he noticed that the dog was staring at something. A small, silver dagger was lying beside the door. Nico swore that wasn't there before.

And then, his eyes glazed over and he was compelled to start walking forward. In a trance, he leaned over and picked up the silver dagger. The hilt was intricately carved with swirls and was inlaid with an amber gemstone. Before he completely processed what he was doing, he lifted the dagger to his hand and made a horizontal slit across his palm. It stung slightly as warm blood bubbled out of the fresh wound, but he could barely feel the pain. He pressed his palm to the door, staining the bronze a dark brown.

The door swung open.
The sudden movement knocked him out of his trance and he stumbled backward onto the floor, using his hand to catch his fall. He gasped in pain, now very aware of the wound on his hand.

The contents of the vault was breathtaking.

There was bronze, silver and gold as far as the eye could see, along with a few stacks of what he assumed was muggle money. There was the currency he could recognize- knuts, sickles and galleons- but there were also a lot of these strange gold coins with owls on them that Nico felt he recognized, but couldn't place how.

In the sea of precious metals something caught his eye: a black falcata sword. The sword let out a faint purple glow and seemed to be drawing the shadows. For some reason, the sword's presence felt familiar, like the smell of his mum's baking, which was strange because he was quite certain that he'd never seen it in his life, he definitely would have remembered it. The aura of death encompassing it was overwhelming.

He walked towards the sword, hesitant at first- he didn't want to go all trance like and cut his hand again-he got closer and his eyes didn't glaze over so he assumed he was fine, and picked it up.

He gripped it instinctively, it was like picking up a pencil, his hand forming a semi-relaxed grasp on the handle. He swung its curved blade and watched as it seemed to cut through the light gleaming off the coins. The shadows in the room seemed to lengthen and the atmosphere in the vault turned gloomy.

He wanted to take the sword with him- this could be his chance to learn more about his family, and why had weird dreams of pits at night, why he woke up screaming bloody murder for no reason, why sometimes he woke up crying after dreaming of sunshine and walking through a strawberry field- but he didn't know how he was supposed to conceal the sword. It's gloomy presence was so extreme that Nico was sure that the minute he walked out of here, he'd feel the burning glares of people wondering what the hell was going on with him. And if he was able to conceal it long enough to get to Hogwarts, he was certain that one of the teachers would find it and he definitely did not want to know what the punishment for bringing a probably-dark-magic weapon into a school was (he also wouldn't want his sword to be confiscated, which it most certainly would be).

So the logical choice was to leave to sword behind, but Nico just couldn't bring himself to put it down! He needed this sword to survive, he had yearned for it all his life without knowing, he was NOT leaving it in this vault.

Then, Nico did something that he was quite never sure how or why he did what he did: he picked the darkest shadow and dropped the sword into it.

He waited for the clank of the metal on stone, but no sound ever hit his ears. It was like the sword had just disappeared into thin air.

Nico reached back into the shadow to pull the sword out, and low and behold, his long, bony fingers wrapped around the hilt of the weapon and pulled it out. He stuck the sword back into the shadow, ran across the room to another shadow and reached into it.

And there was the sword again.

Nico let out a gasp, though at this point it was half-hearted. He'd seen so many weird things in the past hour or so, he didn't really have it in him to be shocked at this strange wandless magic he was doing.

Wait, how long had he been in here? He said that he'd meet the rest of the Weasleys outside the Leaky Cauldron at half past ten, which would've been about forty five minutes after he came in. Now, it wasn't like he was counting, but he was pretty sure it had been more than forty five minutes.

Nico cursed under his breath and hastily scooped up a few handfuls of coins and stuffed them into the purse at his waist. He then stuck his new weapon into the shadows and began the long journey back to the surface. 

Thanks for sticking through that long-ass Gringotts scene. Also, feel free to call out any plot holes, inconsistencies, or grammar issues, I want to make this story as good as possible!