Forest
Midoriya was running with an unconscious Atreus on his back. He thought to himself, "That fighter. Something's familiar about her."
Without warning, Xivu Arath appeared, running beside him. She rammed into him causing him to drop Atreus as he tumbled into the ground. Xivu Arath said, "Didn't think I'd let fresh meat get away did you?"
Midoriya didn't answer as he stood up. Charging up One for All once more, he readied himself to fight, cracking a smile.
Xivu Arath tilted her head in intrigue. She said, "You have to know how outmatched you are. Yet you smile. Are you happy to face someone leagues above you?"
Midoriya replied, "Of course not. But someone taught me that the stronger heroes are the ones who smile through all the hardships."
She laughed and said, "How delightful. I don't know whether that's genuine resolve or underdeveloped optimism. Especially with what happened to your power."
Midoriya said, "What are you talking about?"
Xivu Arath said, "I had a feeling you wouldn't remember. I am the youngest sister of the Taken King. Your previous master. While you were under his control, he made you tell him about your power. And you gave it to him."
Midoriya's eyes widened. Xivu Arath took advantage of his momentary distraction, charging and striking him in the stomach. When he recovered, he said, "I can't let her distract me." He turned to Atreus to ensure he was still ok. Atreus was slumped over in the dirt, but unharmed. Midoriya turned his gaze back to his opponent, who was making her next move. She hadn't summoned any weapons yet, seemingly going with fisticuffs.
He charged at rapid speed, moving at incredible speed and bouncing off the trees. He charged a punch and swung it downward on Xivu Arath. She punched upwards knocking his fist upward past her head, then kicked him upwards in the gut. He flew back but recovered quickly. Xivu Arath quickly rushed him and gave him little time to recover. He was able to jump back right before she slammed on the ground, shattering it to pieces. The pieces flew upward and she punched them towards Midoriya, forcing him to jump back again.
"She won't even give me a chance to breathe. She's so fast.", he thought.
More of the pieces flew towards him and he turned his hand, preparing to flick his finger. He charged One for All into his finger, and flicked it, creating wind pressure that deflected the pieces. It wasn't enough to slow down Xivu Arath's advance as she charged him again. She successfully landed a clothesline and slammed him into another tree.
Midoriya fell to the ground, coughing from the damage his throat and back had just received. Xivu Arath pinned him under her foot. "Impressive. You lasted 30 seconds longer than I thought you would. But it seems you're spent." Midoriya struggled to stand and said, "No. I can still fight. I can still work to protect them!"
"Your power fades away by the minutes. You can't save everyone. It's pure vanity to still think you can.", she sneered. Midoriya charged One for All to 100% through his arm. He slammed the ground throwing the two of them into the air. This released Xivu Arath's grip. He spun through the air, kicking her in the face launching her back. He landed and slid on the ground, looking up to see her flying away through the air. Suddenly, she summoned Kratos' chain blades, throwing them to the ground and pulling herself towards it. Midoriya jumped back to avoid her strike. Xivu Arath said, "Impressive. I didn't see that coming."
Midoriya was grabbing his arm in pain, which Xivu Arath took note of. She said, "But it seems using that much power was less than beneficial to yourself. A cruel irony. You must break yourself to get any use out of your power. Especially against a much stronger adversary that you face alone."
"He's not alone, though.", a childish voice said.
The two combatants looked to the source. It was a young looking boy with blond hair and green eyes. He wore a long-sleeved, high-collared white tunic over an undershirt, a pair of gloves, knee-length black pants, and black boots. In his left hand he held a short sword with seven holes along its green blade and a golden hilt. He was just an inch shorter than Midoriya.
Next to him was an older guy with grey hair, and a red coat with an open collar exposing his chest along with red leather pants and boots. He was as tall as a man.
On his other side was an even younger boy with short brown hair, who was floating on a green leopard pattern pillow. He wore a long orange and aqua sweatshirt with a hood and navy blue sleeves, quarter-length navy blue pants, and short boots with large buttons matching his hoodie. He was a head shorter than Midoriya.
Xivu Arath said, "New combatants? Exciting! May I ask your names?"
The blonde haired boy said to Xivu Arath, "My name's Meliodas. Dragon Sin of wrath."
The grey haired man said, "Ban. Fox Sin of greed."
The brown haired boy said, "Fairy King Harlequin. But you can call me King. Grizzly's Sin of Sloth."
Meliodas said with optimistic naïveté, "So, you're the big troublemaker Thel told us about, huh?"
In the blink of an eye, Meliodas rushes forward, striking Xivu Arath in the stomach and sending her flying through the trees. Midoriya's eyes were wide with his display of power. Meliodas walked to him and said, "Are you ok, kid?"
Midoriya said, "Yeah. That was amazing."
Meliodas smiled and said, "Just one of the perks of living for 3,000 years as the son of the demon king."
Midoriya said, "Wait, what?!"
Xivu Arath you're back through the trees as Ban said, "Story for another time. Look alive, kid!" He pulled out a staff split into three sections, connected by a chain, and he swung it like nunchucks.
King levitated off the pillow and waved his hand. It transformed into a levitating spear that he controlled with his mind. He said, "Chastiefol, first configuration! Spear!"
Midoriya charged One for All to 8%. His arm was still broken but he clenched his fist to continue the fight.
Xivu Arath drew Kratos' frost axe in one hand and her sword in the other. She charged through the space in the trees. King launched his spear at her, and she slid down ducking under it while holding her sword above her. The spear grinded along her sword as they slid past each other. When it finishes she Ban jumped over head to attack Xivu Arath with his staff. She used the axe to hook the staff and pull it to the ground beside her, kicking him through the stomach. It burst out of his back, impaling him. She then rotated and threw him off her foot into the tree.
Midoriya yelled, "Ban!" Meliodas said, "He'll be fine! Come on!"
Meliodas charged and began clashing swords with Xivu Arath. Her speed and strength were noticeably greater than before. It allowed her to keep up with him and not be overpowered. Midoriya tried to attack but she easily dodged his coming kicks while blocking Meliodas' sword strikes. He suddenly dropped his sword, and Xivu Arath's sword swung right between his hand and sword. He grabbed it again and used her momentary vulnerability to his advantage. He quickly stabbed her in the side then ripped his sword through her torso. Black blood sprayed across the forest.
Ban was knocked against the tree by Xivu's kick. He slowly healed, his body regenerating as he stood back up. He grunted and said, "Ok. She's faster than I thought."
King shouted, "Chastiefol, fifth configuration! Increase!"
From behind a storm of knives controlled by King flew from behind. He had transformed his spear into them. Xivu Arath began to regenerate from Meliodas' strike. She used Kratos' chain blades and spun it incredibly fast. This allowed her to deflect the blades. She used her other hand to grab Meliodas and slam him into the ground. She did all of this while evading Midoriya's kicks. When the blades receded, she turned the spinning chain blade and hit Midoriya with the chain, throwing him back.
With her moment to recuperate, her body began to shift and she pulled a hilt from her stomach. This formed into Meliodas sword. Meliodas jumped back from her, frowned and said in a more serious tone, "She copied Lostvayne..."
King said, "You don't think she copied it's power do you?"
Midoriya said, "Are you talking about the sword! What's its power?"
She grabbed the blades with both hands, and before their eyes, she split into multiple copies of herself. When she finished, there were now five of her standing ready to fight.
Ban groaned and said, "Aw, hell no!"
The four clones charged the four heroes. Midoriya was kept on the defensive against one, evading its swings. Meliodas blocked the attacks of another, and King summoned his spear once more using it to defend himself. Ban swung his staff rapidly around to to block another clones coming attacks.
Midoriya yelled, "They're slower than she is."
Meliodas explained, "When I create copies they're always weaker than me. And they get weaker the more of them I make."
Midoriya ducked under the clone's grab and flipped backwards, kicking it square in the chin. It flew back and exploded into smoke. Ban managed to strike another in the head, destroying it as well. Meliodas easily impaled the third one through the stomach, and King used his spear and stabbed the last one through the back.
Midoriya said, "I think that's the last of them."
They looked around and found the original Xivu Arath had vanished.
Ban sighed and said, "She just used those clones as a distraction."
Midoriya's first thoughts were of Atreus. He turned back and saw Atreus still unconscious by the tree. He ran over to him and said, "He's badly hurt. We need to carry him back."
King turned his spear into a pillow and said, "Rest him on here. I can carry him to the Boar Hat. Elizabeth can heal them there."
Meliodas picked him up and placed him on the pillow. Ban picked up Midoriya and carried him on his back. Midoriya said, "I can walk."
Ban said, "Kid, you're in no condition to be walking. You're arm's busted and you just took an absolute beating."
As they started walking (or floating in King's case with Atreus resting on the pillow floating behind him)
Midoriya asked, "How did you guys know where we were?"
Meliodas smiled and said, "We didn't, but it wasn't that hard to track you when you were flying in the air and making all that noise"
King asked, "What was that power you were using?"
Midoriya explained, "it's a power that lets me increase my strength and speed. But using too much of it causes me to break my body. I used it at 100% in my arm. That's why it looks like this. 8% is the highest I can go right now without hurting myself. But that girl we fought. She said her brother made me give him my power when he had me under his control. I don't know how much longer I'll have this before it fades away."
Meliodas said, "Well, the best thing you can do is use it as much as you can before it's gone."
Midoriya began feeling the fatigue of the fight as he was about to pass out. The last thing he said before falling asleep was "Yeah."
