A/N: It's a modern au which may contain two or three parts.

One way of ruining a highschooler's morning is by having 'Maths' on their first hour. 

To rub salt on the wound, the third years were indeed surprised by an unannounced test by their beloved (demon in disguise) teacher, Gray Fullbuster.

But one of the students had a deferring thoughts. 

"Juvia-chan, quit staring at Mr. Fullbuster. He's emitting dark aura." Meredy shook her friend from her daily day-dreaming session.

Juvia got startled and looked around before her eyes fell on the man who was handing her the question paper.

"Take it" 

Gray Fullbuster remained indifferent and went ahead distributing the papers. Juvia pouted and looked at the questions after conveying best wishes to her best friend.

As expected the maths teacher didn't have mercy on his students. Half of the students were sure that they would be doing the revision sheets that weekend.

After handing over the sheets back to their teacher, the students left for their next class.

"Meredy-chan, you go ahead. Juvia will catch up in five minutes."

Meredy-chan smirked and whispered, "Juvia-chan, make sure you don't do any naughty stuff."

Juvia's face grew red due to embarrassment and denied anything like that.

Once the classroom became empty except for Gray and Juvia. The latter made way towards her love interest.

"Ms.Locksar, why don't you hurry up for your next class? Before Mrs.Fernandez marks you absent." Gray said with a small smile before opening his arms, completely contradicting his previous statement.

Soon Juvia closed the gap and hugged her beloved lovingly. As the couple enjoyed their alone time in each other's arms not caring about their environment.

"She won't mark Juvia absent that easily, Gray-sama. So let Juvia get recharged just like you. She missed you, Gray-sama." Juvia said while looking at him before smiling.

"Man, stop giving me those heart squeezing looks. By the way, even I missed you." Gray blushed and looked around before leaning forward to kiss which Juvia reciprocated back.

As the couple were engrossed in their intimate moments suddenly the door opened which caught the couple off guard and made their hearts stop beating.

"That's why, I was against your relationship." Slowly the couple turned around to look at the person who interrupted them.

"Onii-chan"

"Oh it's only you. Man, for a moment, my heart stopped." Both Gray and Juvia sighed in relief and he let go of her.

It was none other than Jellal Fernandez, Juvia's older brother who is a decade older than her.

Jellal hit Juvia's head and scolded her, "Didn't you promise me that you wouldn't do such things inside school campus? Now go back to your class, Erza has already left."

"Sorry onii-chan. See you later, Gray-sama." Juvia left the classroom.

As soon as Juvia's head vanished, Jellal glared at Gray, "Try to act as a responsible adult. I don't want both of your future to be ruined."

"Yeah!! I know. Just I couldn't resist your sister's charm. She has wrapped me around her little finger. Don't worry, I will be careful next time." Gray smiled before leaving the older man behind.

"I didn't expect you to show such drastic changes since last year. Really love can bring out the best version of yourself." Jellal said before following his colleague.

"You are right." Gray grinned.

#

Gray Fullbuster, 22 years old, joined the Fairy Tail High school last year as an intern teacher-student along with his friends, Lucy Heartfilia and Natsu Dragneel who had their specialization in Literature and Physics.

The reason they chose this school was because it was their alma matar.

Even though Gray was close to his friends but showed a cold and reserved personality to outsiders which included his students as well.

He was assigned as the substitute maths teacher to class 2-C, the class where he met his love interest for the first time.

At first, Gray was strict to every student. But girls of his class were head over heels for his handsome face and physique except for Juvia Locksar.

He didn't give any care to their advances and straight away reported to the principal Makarov. 

It was through this event Gray and his friends befriended the Fernandez couple, as Mrs.Erza Fernandez was the head of disciplinary committee.

The same drama continued for nearly six months until Juvia entered his life by storm. All thanks to being knight in shining armour for her.

On the day of Christmas eve, after enjoying the party turn thrown by his college friends. Gray on this way home noticed a group of thugs harassing a girl.

He thought of ignoring it until he took a closer look at the girl and it was one of his students, Juvia Locksar. Luckily, Gray was able to save her before things went out of hand.

"Idiot, what are you doing here this late at night?" Gray scolded her but she stood crying.

Now he began to feel guilty for making her cry and asked her again on a calmer tone.

"Juvia is waiting for her boyfriend. We were supposed to meet here. But he's running late." She said while clutching the gift bag against her chest.

"Do you still believe he will show up now? Look it's almost 11:30 PM. Go back to your home, your parents will be worried." Gray tried to convince her but she was determined on decision.

"Thank you for helping Juvia, sensei. Don't worry about Juvia now, Bora-kun might come anytime." She smiled at him which made her pale face flushed.

"Fine, you won't listen. Do whatever you want. Don't forget to show up tomorrow for school. Bye" He left her there and went to his apartment which was just at the end of that lane.

Luckily, Gray lived on the 5th floor which gave him a clear view to watch his student who stood at the place wher he left her.

"Stupid highschooler" He muttered and closed the curtains and decided to sleep.

It was around 1am when his peaceful sleep was interrupted by a call from Lucy.

Gray wondered what could have happened at her place. But came to conclusions that Natsu might have pulled a prank which could pissed her off.

"Hey Lucy, what do you want at this time? Did Natsu do something?"

"Thank God Gray, you finally attended our call. Hey, did you by chance see Juvia Locksar anywhere? She's missing. And Jellal and Erza are worried about her."

Gray got up and listened to her carefully, "Wait, I saw her few hours back. Just be on call, I will come back."

Soon Gray went towards the window to see whether she was still at the place and as expected she was still waiting for her boyfriend even though she was shivering.

"Stupid Girl!!! Don't she have any self-respect. How can she blindly believe him?" Gray wore his t-shirt and informed Lucy at Juvia was still in that place.

"Good thing you found her, Gray. Wait, let me inform Erza. I will share your address with them. They will come and pick her up. Just go and keep her accompanied. Bye" 

"Sure I will. Bye Lucy" Gray soon left the apartment with a jacket and towards Juvia. He could make out from her face she had been crying for a while.

"Idiot!! You didn't go back to your home. Have you lost your mind? Look at the time and your state. Another one hour, you would have been dead. Stupid, have some self-esteem." 

He scolded her and wore the jacket he brought along with him around her shoulders.

"Sensei, you are right. Juvia was blinded by love and fell for a prick. She stupidly believed even he loved her. But he was using Juvia just as pass time material. Bora-kun, broke up with Juvia and told her not to disturb him again. "

Soon Juvia's crying became louder. Gray, without thinking about anything, he hugged and let her cry on his shoulders.

Once she calmed down, he took back to his apartment and waited for the Fernandez couple to show up. He wondered why they were worried about his student.

Gray gave her hot glass of milk which she reluctantly accepted. He even offered to make something for her to eat knowing she wouldn't have had anything for dinner but she polite declined.

"Hey, you knew he broke up with you. Then why didn't you go back to your home? Looks like your parents are worried, that's why, Erza and Jellal sensei along with my friends were looking for you. At least, you could have informed them that you were staying at one of your friends place." Gray tried to start a conversation. 

Juvia now feeling bit warmed up, looked indifferent after hearing that the other teachers were searching for her.

"Juvia lives alone. Her parents divorced. Just few years back, mama passed away. There's none on this earth to care of Juvia. She only has got herself to look after her, sensei. Sorry for worrying everyone." She bowed down and apologised.

Gray was now confused and wondered if she doesn't have parents then how was she able to live alone. How did she manage on her own?

Before he could ask her any more questions, someone knocked the door and he knew who it was.

"Sit here. Looks they have come to fetch you."

Gray opened the door and there stood the Fernandez couple who had worried expression on their face. Once they entered the living room, they saw Juvia sitting quietly and drinking milk.

"Oh Juvia, you look fine. We were worried about you. Where were you anyways? What happened to your mobile?" Erza sat besides and hugged her.

Jellal remained silent and then thanked Gray for finding her. "Sensei, Juvia is fine. Sorry, her mobile ran out of battery, that's why, Juvia couldn't inform about her whereabouts. Sorry for worrying you, sensei."

"Juvia, please call me onee-San. I'm sensei at school alone. Don't treat as strangers, dear." Erza looked worryingly but Juvia didn't even face her.

Gray was now curious and wanted to know how these three were related. So he broke the silence, "Erza, I didn't know she's your sister. Juvia, you couldn't have told me, Erza is your sister."

Erza looked at Gray and answered, "Gray, Juvia is Jellal's sister. That's how we are related. Come Juvia, let's go back home."

"No, sensei. Juvia will go back on her own. It's just half an hour from here. Juvia can manage." She replied coldly which made Erza sad.

Jellal had enough of this monotonous conversation, went near Juvia and towered over her.

"Juvia, that's enough. Don't act in such rude manners. If you have any problem with me, show it on me not on her. We were genuinely worried about you and whereabouts. Come let's go back to your place. We will drop you there. Now get up." Jellal caught hold of her wrist but Juvia tried to pull it back.

"Let go of Juvia. Juvia is not being rude to Erza sensei. Juvia doesn't want anything to do with you. Leave Juvia alone. 
    Anyways, you didn't want Juvia and left her with abusive mother. You didn't care about Juvia for a long time but now acting up as if you care about Juvia. Stop acting."

Juvia was crying hard and soon Jellal hugged her and the siblings were having their moment.

"I'm sorry, Juvia. I knew our mother was abusive. But she had won your custody. We couldn't take you with us. I thought of bringing you back with me once I had a place of my own. But you had left the oak town by then. 
    It was last year that I saw you in Magnolia and most importantly, in the same school where I was working. But you didn't want to get associated with me. Please forgive me. Let's go back how we used to be."

Jellal conveyed his feelings through words and soon Juvia tears subsided as she could feel his sincerity and apologised to her brother for being rude.

Once the siblings issues was resolved, they left the place after thanking Gray for his help.

Gray was happy to see his student smile to once. Before Juvia left, she handed her sensei the gift which had brought for that prick.

"No, teacher can't accept gift from students. It's not right." Gray was reluctant and gave it back to her.

"No sensei, Juvia insists. It's a thank you gift for saving Juvia from those thugs, then giving some advice and finally, Juvia reunited with onii-chan in your place. 
    More importantly, you took care of Juvia until they came to pick me up. Please sensei, think this as a Christmas gift. Merry Christmas"

After hearing her words, Gray was convinced and gladly accepted it from Juvia.

"Fine, thank you for this gift. Now, focus on your studies and don't go back to that prick. I will make sure to teach that guy for making you cry." Gray smiled.

This was the first time Juvia had seen her grumpy sensei smile which made his face look so happy and handsome. Her heart skipped a beat which made her blush.

"Sensei, your smiling face looks so good which suits you. Juvia's lucky to see that." She said blushing and her words caught Gray off guard which made him embarrassed.

"Now you look cute, sensei, when you are flustered. *click* " Juvia hand gestured as a camera and clicked his flushed face.

As Juvia giggled, Gray's heart beating raised. This was the first time since a while Gray felt like that. Luckily, a fake cough interrupted them and it was none other than Erza.

"Well, Juvia come your brother has started the car. Let's get going. Bye Gray.."

"Bye sensei" Juvia smiled and waved him.

"Bye both of you" Gray waved back but blushed once Juvia turned again to wave him back.

Little did Gray knew how his and Juvia's life was going to be intertwined.