Soulmarks existed long before quirks did, but there was still far less knowledge about the marks than there was about quirks. Soulmarks prior to actually meeting your soulmate were almost always too vague to be very telling. After meeting your soulmate the mark could take on detail or it might grow or even move across your skin. Even then the meaning behind a person's mark was sometimes hard to tell. Some people had marks that represented their soulmate's quirks, others that represented their personalities, or the way they felt about their soulmate, while still others represented the bond they shared or an aspect of their soulmate's personality. It was entirely inconsistent in Izuku's opinion. Nonetheless she loved her soulmarks. Some other students had speculated the pale matching orange and blue stripes on each wrist were because she had 2 soulmates, though it was rare to have more than one. Izuku had looked into it, but found that typically those with two wholly separate soulmates did not have marks that matched each other the way hers did. One fine orange stripe and an identical blue striped on her opposite wrist. No, she had one soulmate.

She told Kacchan she was sure they were both for just one person but he'd only scoffed and said she couldn't possibly know because she was just a deku and what did she know. She asked about his mark and he'd shrugged and said it was on his back, but never told her anything beyond its placement.

Once she and everyone else in her class found out she was quirkless her peers turned cruel. They pitied whoever had to be the soulmate of poor, quirkless deku. Her soulmarks became her lifelines. A reminder that someone was out there for her to love. The other students leered and made fun because surely her soulmark would be unrequited. It was a sad thing and it was rare, but then so was being quirkless in this day and age. She did her best to prepare herself for the possibility that her soulmate's mark would not be for her. She would love them anyway and hopefully they could at least be friends. Izuku instead focused on her goal. She would become a hero. Even without a quirk or a soulmate she would smile and protect the people. More than anything that's what she wanted.

Later, when she ran into the river to help Kacchan after he'd fallen he'd stared at her hand for several seconds before standing up and shoving her down. He sneered and said he didn't want help from a deku that didn't even have a quirk. Izuku had sat in the water thoughtlessly tracing the orange ring around her wrist long after Kacchan and the other children were gone. It became a habit after that. She was constantly touching her soulmarks. Anytime she was anxious or upset or thinking, which translated to nearly always. She felt like there was a steady, determined strength behind her marks and she drew on it to calm and reassure herself. She would prove them all wrong. She could be strong; she could be a hero.

That stubborn and defiant thought lived on for years and fueled her to further study heroes, not just All Might, though he would remain her favorite. She filled notebooks with observations, plans, costume designs. Anything and everything related to heroes or becoming a hero filled their pages. There was a lot about different quirks and occasionally she would jot down if a hero's soulmark was public knowledge. There weren't many. For protection most heroes covered their soulmarks with their costumes or wore skin patches to cover them up. Others lied entirely in order to misdirect. She sometimes idly wondered if that was why Kacchan had stubbornly never shared his mark with anyone. Practice for the future when he was the number one hero? Not that a random smudge on his back would actually tell anyone anything. It wouldn't be a concern until it activated when he met his soulmate. Regardless she was probably overthinking it.

Izuku was still scribbling out the plethora of things she picked up from the hero battle she managed to witness that morning as the teacher walked into their classroom. "Since you're third years it's important to start thinking seriously about your futures! I've got forms to fill out, but that said, you're all planning to go the hero course, right?" He gave a defeated smile as the class erupted in a chorus of agreements, each student proudly displaying their quirk.

"Oi! Don't lump me in with these extras!" Izuku immediately snapped to attention at the strong voice that rang out over the chaos. The other students responded with angry shouts, offended by his arrogant and standoffish attitude. Izuku just slunk into her chair, trying to disappear. Kacchan kept going, seemingly spurred on by their classmates, "Just shut up, you damn losers!"

"If I remember you're aiming for UA, right?" asked the teacher as he flipped through some sheets on his clipboard.

The classroom went quiet for a moment before everyone started gossiping about how the national school was too hard to get into. She dropped her head on her desk. She had a bad feeling.

"That kinda thinkin' is why you're all just extras!" Katsuki Bakugou jumped easily onto his desk as if to emphasize that he was above everyone else. "I aced the mock test! I'm the only one from this shithole that could possibly make it into UA! I'll surpass All Might himself and become the top hero!"

"Midoriya, you wanted to go to UA, too, right?" the teacher drawled. She froze. The entire class was glaring at her before they collectively burst into laughter.

"Midoriya? No way!"

"You can't become a hero by studying hard!"

She opened her mouth to argue only to fall back at the sudden impact of Katsuki's fist on her desk, causing the poor piece of furniture to burst into flames. "Hey, shitty Deku! You don't even have a quirk, but you're trying to compete on my level?!" He looked manic.

"No! Kacchan! I'm not trying to compete or anything!" She crawled backwards to get away from the angry boy, waving her arms frantically. "It's just it's been my dream since we were little and- and I won't know unless I try..," she'd hit the wall. No way out.

"Unless you try, my ass! You taking the test for fun or something?! You're quirkless, what're you supposed to do?"

The teacher reestablished order after that but Izuku didn't look up from the burnt wood of her desk the rest of the day. She traced the lines on her wrists as she tuned out the voices around her.

It wasn't until the end of the day, as students filtered out of the room, that she peeled her eyes up and tugged her sleeves down. She took a deep breath as she packed up her things. As she reached to put her heroics notebook away, it was snatched up by Kacchan. "I'm not done talking, Deku." She shifted uncomfortable under his glare.

His posse came up behind him and asked what he was holding. Kacchan lifted it lazily to their eye levels, not taking his eyes off of Izuku. "Hero Analysis for the Future? Seriously?" They laughed hysterically. She didn't think it was that funny.

"Give it back!" She said, standing and reaching out to pluck it out of Kacchan's grip. He lifted the notebook out of reach and slapped the cover, causing it to explode. "That's mean!" She started to argue only for the boy to carelessly toss the charred notebook out the open window behind him. Izuku stared listlessly at where her notebook had disappeared.

"I'm going to have the title of being the only student from this shitty junior high to make it into UA, got it?" he asked, slapping his hand down hard on her shoulder making smoke wise from her burnt uniform. "So don't apply to UA, fucking nerd."

He turned to walk away, his friends making snide remarks about how weak and pathetic she was. "If you really want to be a hero, here's an idea! Believe you'll be born with a quirk in your next life and take a swan dive off the roof!" Izuku whipped around, mouth open with a retort only to meet angry red eyes. Katsuki flared his quirk threateningly and she went still. There was nothing she could say. She would just have to prove them wrong. She went outside to fish her notes out of the pond, muttering about how Kacchan shouldn't recklessly go around telling people to kill themselves and how her dreams were being turned to fish food as she found the koi nibbling on the burnt edges of her booklet.

Author's Notes: AAAAAAHHHHHHHH! Soulmate!AU with fem!Deku I'm garbage, but whoa this is my first fanfic? Honestly I'm a bit disappointed that I'm not putting more effort into this, but hey maybe I'll rewrite some of this later. The next chapter is already written, but I'm gonna wait and see what happens. No idea how this works. The next chapter will probably just cover Izuku meeting All Might, and maybe I'll add the sludge incident.