Luffy x Demon! Reader

Wars

You all arrived at the island where your sister's hide out was.
"There it is. The Island Of Darkness. It wasn't always like this. It was once a beautiful island." You said.
"Why would she do all of this?" Robin said. "Well I can't really remember why but I know how she became so dark."

*Flash back to 12 years ago*

"I can't believe i'm a demon now. And I can't even show my new real self." You said sitting next a river. You looked down at your self in the water and tears started in the corners of your eyes.
Then all of sudden you were kicked and you fell into the river. "*gasp* What? Hey who was that?!?" You yelled as you crawled out of the water.
You looked back and saw your sister standing there with her eyes a shade of red. "Hey (S/n) why would you do that?" She said nothing but she flew at you and pushed you up against a tree. You were bruised and had cuts all over you. She then laughed evilly and looked at you with a devilish smile and spoke. "Wow your really are a new demon. You couldn't even sense that I was here could ya." "Hey let me go (S/n). Why are you doing this?"

"I'm doing this to prove that i'm the better demon! And there's nothing you can do about it." She said. You were mad REALLY mad.
"And once i'm done with you and those other annoying brats. I'll destroy every last human and unleash a army of demons!" She laughed.
'I can't let her do this. I can't let her hurt anyone. I have to do something.' You thought to your self. "Well let's go a head and finish you off." She said as she rose her hand to blast you.
"NO!" You yelled. But when you did a glow surrounded your body and your eyes were red. You then used you claws to cut her in the face.

She let out a painful cry and let you go. She had a scar but it turn black and disappeared. "Ahh! You little brat!" She yelled as she ran towards you. But punched her in the face when she got close to you.

"That's it!" She said darkly she then turned full on demon. She could do this because she had more training. She ran towards you and attacked you. She also blasted you with one of her rays and attacked you when you were off your guard.
There you lay weak and helpless. But before she could kill you your sisters started to beat her. She then flew away knowing she couldn't take both of them on at once.
"We have to get (Y/n) help right away!" Crystal said. Then Fawna carried you back to the house they were staying at. You healed but ever sense then you vowed revenge on your sister. "I can't let her get away with this. I'll never forgive her for what she has planed for us!"

*Flash back over*

"How terrible!" Nami had said as she hugged you. :It's fine Nami I'm stronger now I'll destroy that demon!"

They all nodded and were ready to fight. When you got off the the sip you were all attack by a swarm of demons. '
"Everyone stay behind and deal with these guys I'll go with (Y/n) and everyone else!" Luffy's crew began fighting them as you guys ran off to defeat (S/n).
"Luffy will they be ok back there?" You said with worry. "There strong they can handle it I know they can!" Luffy said back. You nodded and kept running. (Or flying whatever you want)


Then there was stronger demons came up and began attacking you all. "(Y/n), Luffy you guys keep going! Crystal said "Yeah we got this they don't seem too tough!" Fawna smirked. "It will be ok!" Sky said Akala just smiled but she was really worried.
"Ok just don't get killed!" You yelled. They then nodded and kept fighting.

*Time Skip*

You then arrive to where your sister was waiting for you.

"Looks like you made it. Huh little brat?" She said to you smirking
"Yeah I made it now I'm gonna kick your butt!" You yelled back