FairyTail's Revenge (ROLU)

Lisanna part 1

RECAP
Lucy was fighting Zeref they broke the guild doors and she yelled that this was her and the team's fight.
LISANNA'S POV
I was just walking towards Kinana with a drink in hand when the doors burst down and a girl landed on top of me after being thrown. "You bitch!" She screamed. I was totally offended cause I thought she was talking to me. "That hurt like hell!" She then got off and did an Elemental dragon roar. "What!?" She screamed wandering why we were all staring at her probably. That's when everyone noticed Zeref standing their at the used to be door. We all got into a fighting stance ready to defeat him. That is until she yelled again. "STOP THIS IS EVERYONE WHO WENT WITH ME AND MY FIGHT AGAINST ZEREF!!" That's when the whole group including 'my' Natsu got into a fighting stance. I was outraged. But what she said next shocked me.
LUCY'S POV
"Oh my gosh I am so sorry I hope we can become great friends after we demolish Zeref," I said to the white haired girl who looked new. I then turned back around towards Zeref and did a celestial dragon wing attavk on him. (Sry I forgot how it actually went if that is wrong) that's when we all started fighting him but that wasn't enough and it was time for me to do my new power combined with all of our fairy magic. 'everyone use your fairy magic at once' 'ok' they said through the telepathy we all shared. "Fairy/music dragon roar" once it hit they looked at me cause they didn't know about the Music Dragon Slaying magic. But that didn't surprise me what surprised me was that a girl with blonde hair like mine but a lil' lighter with black natural highlights like mine and yes mine are natural along with her hair to the beginning of her butt, baby blue eyes unlike mine are green and blue and hazel she wore ripped denim shorts with black tights with multi colored flats and an oversized 5SOS shirt. She did a music lighting dragon roar at Zeref and knocked him out for he didn't have any magic energy left after defending and fighting us.
??? POV
I was walking around Magnolia when I heard a familiar voice from my childhood scream. That's when I ran and ran as fast as I could to this building that has a banner with a guild mark on it and at the 'gate' entrance it had FairyTail. I didn't stop and kept running to what I'm guessing used to be the door. That's when I saw him and her. It was Zeref, a group of people, and ...
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GOMENSAI GOMENSAI I'm so very sorry this is so short unlike the last chapter but I had to do a cliff hanger. Ok the reason I did a cliffhanger was to ask you people a question. My question is what should this mystery person be to Lucy-chan. Here are the chooses:
Sister
Cousin
Long lost friend
Your choice: although there isn't really anything else but if you think of something and you want that say it.
Anyways again GOMEN NASA I (I'm sorry) also
ARIGATO AND SAYANORA MINNA-SAN