As a kid, Adrien was always covered in bruises. Most kids are, it's just a part of childhood. But sometimes those parts become a hassle when you're a model, and need those bruises covered.
It took Adrien's father a while to realize that the bruises weren't actually his son's doing. Once they realized that that amount of bruises couldn't be coming from their son who almost never did anything other than read and pose for a camera, Gabriel and Emilie came to the conclusion that they were from Adrien's soulmate.
Of course, this only seemed to further Gabriel's agitation with the blemishes, considering there was nothing he could do to stop them from popping up. Emilie on the other hand, couldn't help but feel terrible for the poor little girl who seemed so accident prone.
As Adrien got older, the bruises became more sparse. And trust me, he wasn't going to complain. He had half a mind to, once he finally found this girl, wrap her entirely in bubble wrap- for both their sakes. It was not fun to wake up to a fresh new set of bruises on his knees, scrapes on his elbows, and pinpricks on his fingertips. What this girl got up to in her free time, he had no idea.
His only solution for the time being was to be as careful as possible- seeing as she was causing enough pain for the both of them and then some. He often found himself wondering if maybe she did some kind of violent sport, like hockey, or if she just really was that clumsy.
Marinette couldn't remember a time where she didn't have at least one bruise somewhere. She could remember, however, the massive amounts of guilt she felt when her parents finally explained to her what soulmates were, and how they showed themselves.
Since then she had tried to be more careful, really, she had. But as a natural born klutz, that was a difficult task. She often tripped over air, ran into walls, and hit herself on rebounds. She didn't know how she got such bad luck, but there wasn't much to do for it. She started to gain more balance as she grew- thank God- and once she met Tikki and became Ladybug, she was almost at the normal level of klutziness. That is, normal for nine year olds. Not fourteen year olds.
And the same day she met Tikki, she met Adrien Agreste. The wonderful, sweet, shy, adorable Adrien Agreste. But no matter how hard she looked, or how often she had Alya ask, he never seemed to have a single bruise on him. This of course dashed all hopes that maybe he was her soulmate.
When Adrien first met Marinette Dupain-Cheng, let me tell you, he was shocked. Never before had he met a girl who was as clumsy as she was. But after the gum incident, he was a little too afraid to pry into her life- she didn't seem to like him much. But of course, he was already head over heels for Ladybug by that point, so he wasn't too upset. In fact, he had never had more bruises than he had after that first akuma attack. And Adrien knew for certain that maybe only half of those bruises were actually his.
But really, how could he tell if he didn't feel most of the hits when in the suit? So he had to try and remember as many of the hits as he could. And whenever he brought it up with Ladybug, she got rather defensive. He wondered if it was because of her want to keep their identities secret, or if there was another reason.
Soon he had turned sixteen, and had been Chat Noir for two years. The bruising had gotten to such a confusing level he gave up trying to guess at who his soulmate was. Besides, most of the time he was able to hide them or they weren't too terrible, and went away on their own within a few days. And now they were mostly on his legs and back, which could have been from literally anyone.
So when he came in one day with a massive black eye, Nino was pretty surprised.
"Dude," he whistled, "nice shiner."
Adrien grumbled incoherently and pulled out his textbook.
"How'd you get it?" Nino asked.
Adrien turned and glared at him- as best he could anyways- and deadpanned, "I woke up with it."
"Ooo, again? That poor girl, bro. I wonder what the hell she gets up to in her spare time."
"I don't know, but I sure hope she's practicing medicine or something." Adrien said. Nino nodded in agreement.
The door popped open and Alya walked in, followed closely by an exasperated and tired Marinette.
"I just don't know how it happens, Alya!" She was saying quite loudly. This attracted Nino's attention. As soon as Nino's eyes landed on her, his mouth dropped open and he looked back to Adrien before whipping his head back towards Marinette.
"- Like, why was there even a wrench there? I don't even know how to use one of those!"
Alya laughed. "Obviously, otherwise you wouldn't have that black eye-" She stopped and her eyes widened comically as she saw Adrien.
Marinette bumped into Alya and groaned. "Alya, what the-" She peered around Alya's shoulder and nearly fell over.
"I'm a terrible reporter." Alya bemoans, hanging her head. Adrien finally looked up with a curious expression to see what was going on.
Upon seeing Marinette's matching black eye, his mouth drew into a frown. "Oh no, Mari, what happened?"
Marinette blanched even more, if it was possible. "I-I-I-I-I… Uhhh eye you me black oops!" She squeaked.
"You broke her." Nino said. And then it clicked for him, and he was laughing. Hard. All he could think of was all those times as children when she had run into everything and fell down everything and tripped over everything and he is no longer functioning.
"What? Nino, why are you laughing? That's not nice!" Adrien admonished. Alya looks between Mari and Adrien a few times, gobsmocked. She face palmed at the boy's stupidity.
Getting a sudden idea, an evil grin spread across her face as she took off her messenger bag and swung.
It connected with Marinette's side with a loud smack! Sending her tumbling to the ground. She cried out as Adrien lost the air in his lungs and gripped his own side in pain as he topples from his chair.
He looked around at his three friends with wide eyes. "I think I just fell for you."
"What?!" Alya and Marinette cried.
Nino started laughing hysterically again, throwing in kissy noises every time he had the air only to collapse into cackles again.
"Nino, give it Agreste." Adrien said, standing up and brushing off his jeans. Marinette wheezed, the puns coming out of nowhere. Alya looks between the two again, still confused.
Marinette looks at Adrien again- her soulmate- and all of sudden everything makes sense. And now she wants to kick herself for being so blind. And as the puns continue to spew from the still confused and semi- out of it Adrien Agreste, she now knows who Chat Noir is. Because only he could spew such horrendous jokes in that quick succession.
"That really hurt, what the hell just happened?" Adrien asked, sitting carefully back in his seat with a wince. He looked back to where Mari was still on the floor. "Mari, are you okay? You're still on the floor… Oh. Oh. So that's…?" He pointed to his eye and looked to Alya for help. "That's how I got this? Wow. Ok. Um. Yeah that just happened. Wow. Mari, can I, can I like, I don't know, wrap you in bubble wrap? Or something? Please?"
The akuma alert rings out as Marinette tries to restart her heart. Alya's face stretches in a wide grin and then she's grabbing Nino's hand to run after it. Wherever an akuma is, Ladybug and Chat Noir are sure to be close behind. Besides, her best friend would still be soulmates with Adrien Agreste when she got back.
Without thinking, Adrien takes off and transforms into Chat Noir, Marinette close behind. But halfway down the hall, she remembers that he doesn't know yet, and runs back the other way to transform somewhere else. However, Chat gets transformed first and is on his way to the attack when he finds Mari pushing through the large crowds.
And being the wonderful knight he thinks he is, he swoops down and picks her up, depositing her somewhere safe.
Marinette blushes and manages somehow to hold in her coos until after he's gone.
"Marinette! The akuma!" Tikki chides.
"Oh. Oops… Right. Tikki, spots on!" And with that, the red clad hero was off on her own way.
"What took you so long, M'Lady? You're late!" Chat Noir called to her as she landed a few feet from him, yo-yo at the ready. She blushed and giggled, earning her a curious cock of the cat's eyebrow. "Ok-ay then… The akuma's in her purse." He said, nodding his head towards the akuma girl swathed in pink robes. Apparently she had gotten mugged and her new wedding ring had gotten stolen.
Ladybug nodded determinedly, swinging her yo-yo and dashing towards the victim. Chat Noir joined in as they resumed their ever constant dance between them and Hawkmoth.
Half-way through the battle, the akuma swung her purse which connected with Ladybug, sending her flying. She hit a wall before falling on her ankle. A spear of pain shot up her leg as it twisted under her and she collapsed.
Chat yelped in pain as well, looking over at her in confusion. "But I thought…?"
Ladybug gave him the best deadpan look she could. "Are you serious right now, Adrien? It's me. Marinette."
Understanding dawned in his eyes, followed quickly by shock, exasperation at himself, and awe.
Ladybug groaned. "Let me just die here."
Somewhere in Paris, Hawkmoth stood in his evil lair.
"Well this is… Hawkward."