This will take place a couple of month after the first part The Crystal story

Y/N POV

It was a couple of months after the "incident" that happened during the mission where Mira and I took two months back. Mirajane remained buff as hell from the crystal but I didn't mind. After some time though Mira got used to her new size and strength with my help and the other members of fairy tail giving her the encouragement she needed to get used to it. Anyway after session that we had that night, Mirajane and I became a couple and we would go on dates every now and then. Some time during the first month after that quest the other members and I went on different missions to raise enough funds to upgrade the guild so Mira wouldn't always have to duck to avoid walking into the rafters. At the end of the first month we hade raised enough and upgraded the guild. Mira was really happy at what we did for her and to celebrate we all had a party that night. I was in the Levy's little library looking up any information I could find on that crystal Mira and I found in the cave. I was looking through the last few pages of this one book as I was about to give up I saw something on the last page that caught my eye. I flipped to the final page and found out the crystal was called the 'Heart of Strength'. The crystal was locked in the cave after it's power was too great for anyone to control causing them to fly into a blind frenzy from the overwhelming power coursing through their body. The only way it will stop is to let use up all of it's power which will happen when it uses it's power on three victims.

Meanwhile in the cave...

The crystal that had shattered during the mission started to shake as the pieces started to glow a dark purple as dark energy shot out of it every few seconds. All of a sudden the crystal shot up in the air as even more dark enerhy shot out of it at random intervals before the crystal put itself back together. Then the evil looking crystal flew out of the room where it was found before flying out of the cave to find it's next target. Not that far away from the cave Minerva was walking along the path nearby. The crystal was flying above the tree line looking for someone to use it's power on when it saw Minerva. It flew towards her and stopped in front of her floating in the air. "Hm, what's this?" Minerva said as she stepped toward the crystal. As she got closer to it, she sensed the immense power inside of it. "Yes, now this is what I've been looking for." she said as she grabbed the gem. As thoughts of proving to her guild that SHE is the strongest mage went through her head, the crystal shocked her just like it did with Mirajane but unlike her she managed to stay upright and hold on to the crystal. "Hnnng, damn crystal." she said while glaring at the crystal as it had shocked her. All of a sudden she felt her body rack with pain as she almost fell over. Her eyes widened as her body was slowly growing and filling with muscle and immense power. Her outfit was slowly shredded to pieces as her legs lengthened and gained a ton of muscle. Her legs stopped growing as she was almost the same height as Mirajane. Then the growth made it's way to her arms as they grew ridiculously large from the sheer amount of muscle. As the growth finished with her arms it made its way to her body as she swelled up with muscle quickly gaining a very noticeable eight pack. Her breasts were the next to grow as they reached the size of twin size mattress causing her to let out a groan of pleasure. Her growth had finished but she wasn't done yet as she grew horns and a long demon tail. The color of her skin also slowly turned red as her teeth elongated into sharper versions of themselves and the scleroses of her eyes changed black and her irises turned a bright red. As her transformation was finished she took some time to admire her new muscles and power before looking at a nearby town then all of a sudden she had a grimace on her face before roaring out "GRAAAAAAAAH!" losing herself to the sheer amount of demonic energy inside of her now. As she breathed in and out she said "Must stay...in...control..." she groaned out before letting out a scream as she lost control and after letting the rage take control of her she lumbered towards the nearby town with the thought of destroying everything in her path.

(A/N: Just imagine Neo Minerva with a long demon tail, sharp teeth, red and black eyes, and red skin)

Y/N POV

I finished reading the last pages of the book about the crystal when Mira barged through the door almost breaking the new big door in the process. "Y/N! We have a huge problem. A nearby town is being attacked my a monster and the town requested help." "Okay, I'll get my gear ready as fast as I can." I replied back to her before getting up from my chair and leaving the room. I got my gear ready as I made my way out of the guild and walked to my destination. It almost night-time as I was running along the path to the nearby village. After about ten minutes of walking, I could see the fire and smoke coming from the village so I picked up my pace and ran towards the place. I entered the small village to see only destroyed building while the other remaining buildings were on fire with people fleeing for their lives. I ran through the place trying to find the monster that caused all this destruction. I stopped in my tracks as I came across a large figure smashing a building to pieces. My eyes widened as I saw who the "monster" actually was. "Minerva?!" I whispered to myself. As soon as I whispered that Minerva turned her head toward my direction making me gulp. "Shit, the demonic energy must have enhanced her senses!" after saying that I had to quickly jump out of the way as she lunged at me. I ran away a little bit to get some distance from Minerva to charge up my pacify spell to quell her rage and pacify her. During this time she would leap at me to try and kill me while roaring and yelling "kill, kiLL, KILL!" which would in turn cause me to roll or dodge her strikes as I was charging up my spell. A couple of times, she had nearly succeeded in killing me after she got me trapped in a corner.

Twenty minutes later, I had finished charging my spell I leaped back avoiding another one of her strikes. I raised my hand and aim my glowing F/C magic circle at Minerva as she looked at me and ran at me. I unleashed my magic at her just as she was about to punch me but by the time her fist was raised, my magic had already taken its effect. She bent down on her knee as her rage dulled and she regained her senses. "Ugh, where am I? And what happened to my body?!" she asked after shaking her head around. "To sum up what happened. You went on a rampage after becoming overpowered by the demonic energy inside of that gem which also transformed you so I came here to snap you out of your anger with my pacifying magic." I replied back to her as I pointed to the evil gem that was lying on the ground a couple of feet away. "Anyway you better get back to your guild before they get worried." "...I'm not part of Saber-Tooth anymore since my father who is also the guild master kicked me out for being too weak." she reluctantly told me. "That is an extremely stupid reason to kick someone out of a guild. But don't worry if you want you can join Fairy Tail, I'm sure everyone won't mind an additional member." I smiled at her. "Yes, I would greatly appreciate that, thank you..." she said with a small smile which was rare for her to show a genuine small without all the arrogance. It seems my magic also cured Minerva of her arrogance. "Now before we get back to the guild, I need to take care of this gem." I walked towards the gem and knelt down before placing my hand above it. "During the couple of months that had gone by after my first encounter with this crystal or gem, whatever you want to call this thing, had grown my girlfriend, Mirajane. I studied different types of magic to try and contain this so it doesn't cause anymore trouble."

After finishing up my little speech, a bubble of magic had appeared around the crystal. I shakily stood up because the spell I had used uses up quite a bit of my magic and strength. "Are you alright?" she asked me worriedly. "Yeah, I'll be fine. I've had worse done to me." "Come on let's head back to the my guild." I said to her as I motioned her to follow after me with the crystal in the orb floating next to me. When we arrived at the guild, I opened the big door to the guild and entered with Minerva following behind me. I made my way to a backroom of the building and stored the crystal behind some crates and barrels. "Hopefully no one will mess with this thing while I'm gone." I said to myself as I left the storage room. As I left the storage room I told the others that Minerva and I were heading home since it was getting late. I was walking towards my house as Minerva was not that far behind me. We reached our destination, I walked to the door and unlocked it which then I opened the door so Minerva and I can get inside. Minerva though had to duck down to enter the house due to her current size. "So do you want anything to eat or drink?" I asked her politely. "No, I'm not hungry or thirsty but thank you though." All of a sudden she picked me up causing me to let out a yelp. "So I thought of a way to you for helping me snap out of my rage earlier." "Uh, how will you repay me?" I asked her nervously. "Oh I think you know how." she replied slyly causing me to gulp. She carried me to my bedroom where she threw me on my bed before taking my clothes off trying not to rip them in the process. She then lined up my increasingly hard shaft with her pussy before dropping down onto it causing her to let out a moan while I grunted from the pleasure. Minerva then began to bounce up and down while being careful to not break me like a pencil. During the sex we were having Minerva reached up and grasped her huge breasts and began to kneed and pull at her breasts while moaning. After a good while of fucking each other I felt her climax with her juices running down my dick causing me to groan out in bliss then release my seed deep inside of her. She then collapsed next to me while catching her breath while I did the same. Soon after my eyes slowly started to close with me falling asleep and with Minerva following soon after with a smile on her face.

(A/N: Sorry about not finishing this. I finally got someone to look at my computer and they managed to fix it so now I can get back to making stories :) )