(Inspired by "The Perfect Girlfriend" from Ben 10 Ultimate Alien, also set in modern times.)
Meliodas had been acting strange since he changed his mind about going on tour. He had been overly nice, always thinking about what would make Elizabeth happy. Normally, this would've been a good thing. If it weren't so suspicious.
He didn't seem to care at all about the tour, or himself. He only cared about Elizabeth and what she wanted. Her friend Elaine was immediately suspicious of Meliodas' one sided affection, same with Ban who was best friends with Meliodas.
He went to the mall with Elaine and Ban, but Elaine had gotten hurt by falling down the elevator shaft. This incident only made Elaine more suspicious.
She had asked Ban to spy on Meliodas for her, see what was going on. He did exactly that, he followed Meliodas and Elizabeth when they went on a date to the movies. Meliodas had suggested Vampire Summer, which made no sense since he hated vampire movies. He also said something about the girl picking the movie, and he didn't even watch the movie. He spent the whole time staring at Elizabeth lovingly.
Something was definitely wrong.
When Elizabeth had to leave for Princess business Meliodas urged her to go, which didn't make sense since they got in a fight over it last time. After she had left, Ban followed Meliodas but then red and blue demons appeared out of nowhere and stared attacking him.
Thankfully Elizabeth came back and took care of them. Ban told Elizabeth what he had learn and while Elizabeth was reluctant to believe that Meliodas wasn't he he said he was, she still had to check for herself. She went to his house to talk to him, but his father answered instead and told her he was in Europe competing in the tournament.
Elizabeth went to her own house to find Meliodas waiting for her on the door steps with Chili fries. She decided to go along with him.
Which brings us to now...
"Who are you?!"
She realized that the boy next to her wasn't Meliodas. As he was competing at the Tennis tournament. She saw him on the TV, a replay from the day before.
Elizabeth watched as "Meliodas" rose from the couch.
"Elizabeth, I did everything you asked, and even things you didn't ask-"
His body was engulfed in darkness and his voice distorted and changed into one Elizabeth never thought she would hear again.
"...and I always will."
Elizabeth's jaw dropped in shock, she blinked as if to make sure she wasn't seeing things.
"Estarossa!"
Before her stood her old friend Estarossa, who was also Meliodas' younger brother. But, he was consumed by darkness a long time ago. Or at least, that's what they thought.
He looked exactly the same since the last time she saw him, almost identical to Meliodas. The only difference being his silver hair and his lilac eyes.
"I was Estarossa, then I was Meliodas. But if you don't like them..."
He shifted into several different boys - Elizabeth noticed the darkness covering him every time he changed - before changing back into his original form.
"I can be anyone you want me to be."
Elizabeth glared at the silver head.
"You almost killed Ban, you used your dark magic to create those demons!"
"He was following me! He was trying to keep us apart!"
"And that elevator, you hurt Elaine. You tried to crush me with it!"
It was Estarossa's turn to glare, he pointed accusingly at Elizabeth.
"You're the one who made it fall! I used my darkness to stop it!"
"The darkness lets me do anything, and all I want to use it for is to give everything you want!"
"What's wrong with that?"
Elizabeth frowned. He hadn't changed, he still can't think for himself. It wasn't healthy.
"Estarossa, what do you want?"
He looked confused.
"Does it matter?"
"It does. Ban's changed - and for the better - since he's been with Elaine. If she had just done everything he wanted he'd still be the same old Bandit Ban."
"I can be more like Elaine, if that's what you want."
"It's got to be what you want Estarossa."
Estarossa looked at her with a pained and longing expression.
"Don't you understand? I just want you."
Elizabeths expression hardened.
"That's not enough."
Then Elizabeth's doorbell rang. She opened it and saw Meliodas, the real Meliodas.
"Meliodas!"
Meliodas smiled at her.
"I came back on the first flight. I don't play again until Tuesday so I thought I'd improvise, and spend the weekend with you!"
He walked passed her and into the house happily but stopped when he noticed Estarossa. The silver haired boy glared at him with his arms crossed and an annoyed expression on his face.
Meliodas' eyes widened as he took a few steps back towards Elizabeth.
"E-Estarossa...? Is that you? How? I thought you were..."
He looked at Elizabeth, pain and confusion and multiple emotions in his emerald eyes. Her heart ached for her boyfriend, Estarossa was his little brother after all.
"Long story..."
Estarossa uncrossed his arms.
"I'll make it quick."
His body was engulfed in darkness once more. It wrapped around his body and formed into clothes. His eyes changed from lilac to blood red. The demon mark appeared on his forehead. (He basically looks like his assault mode except he's younger.)
He shot Hellblaze at Meliodas but Elizabeth appeared in front of him and blocked the attack. Estarossa manifested dark tendrils and grabbed Elizabeth, lifting her into the air and throwing her through the wall and outside. She groaned.
Meliodas ran towards her.
"Elizabeth!"
Dark tendrils wrapped around his arms and legs and lifted him into the air. Meliodas shouted and grunted as Estarossa toyed with him in the air. Elizabeth got up and ran towards the demon.
"Put him down!"
"Or?"
Elizabeth's hands glowed and she threw 4 orbs of light at Estarossa. He hissed as they blinded him and he reduced himself into a blob of darkness. The tendrils let go of Meliodas, Elizabeth caught him and set him down.
She then turned to the mass of darkness and was about to use an Ark before it changed into Meliodas' form again.
He looked up at her with a scared and confused expression. Elizabeth hesitated and her fist shook, then Meliodas' face changed into Estarossa's and darkness sprouted from his hair and suffocated Elizabeth.
"It's - *wheeze* - in...m-my....lungs!"
Estarossa - still in the form of Meliodas - smirked as he watched Elizabeth wheeze and cough. Meliodas watched, horrified and looked desperately at his brother.
"What are you gonna do?! Kill her?! If you can't have her no one can, is that it?!"
Estarossa's smirk disappeared as he looked at his older brother.
"I...I love her."
"You don't know what love is!"
After Meliodas had said those words, the darkness stopped suffocating Elizabeth. She coughed the rest out of her lungs and fell on her hands and knees. Estarossa watched as Meliodas rushed to her.
"Are you okay?"
Elizabeth nodded as Estarossa approached them.
"Maybe I don't know what love is,"
His sad and lost expression changed into one of resentment.
"But now I know what hate is!"
He dissolved into a mist of purple and went down the sewer.
"You'll see me again."
Elizabeth and Meliodas watched with sad and concerned faces.
Was there any saving him now?