What if...
There is continuation of Error being a bad boy and Nightmare being a strict teacher?

Haven't read it yet? Read "What If" in this book!

Error blushed softly as his head kept thinking of a certain history teacher named nightmare. He couldn't stop thinking about him somehow and everytime before he sleep, He always keep checking if the next day will be history lesson. He became quiet less scary and destructive day by day because of that distraction.

He just became more confused and deep in thoughts. He kept on procrastinating in the class and did nothing except stare at the window, Having a deep thought of his own fantasies. He sighed softly as today is one of the day. He was staring at the window as he ignored what's happening in the class. He was fallen in a deep fantasies till the teacher yelled at him.

"ERROR! HOW MANY TIMES DID I CALL YOU!?" Mr. Nightmare yelled as he slammed his book in front of Error's eyes. Error eyes widened as he let out of surprised yelp and fell from his chair, landing on his butt with a loud sound. "Ouch..." he muttered in pain as he rubbed his butt, Looking at the teacher in front of him with such a pained expression.

"Present." He muttered as he slowly stood up nd sat back on his chair. Suddenly the class bursted in laughter, Error looked at them in confusion as he saw nothing was wrong in here. Nightmare just face palmed and looked at his student who didn't mind paying any of his attention to the class.

"I asked you to answer the question Error. That's why you need to pay attention in the class." He sighed as he pointed to the question 23 in the page 69. Error chuckled in embarrassment as he started frowning a little bit, Thinking something as he stared at Nightmare's face. Sometimes he wondered how his homeroom teacher yet history teacher could be so flirty yet strict at the same time.

Nightmare sighed as he saw his student conflicted face yet dazed in his thoughts again. "...Error. Meet me in my Office after school. I have something to tell you." He spoke strictly as he walked back to the whiteboard and started teaching the class again. Error frowned, Screaming why inside his head.

[After school]

Error nervously dragged his feet to Nightmare's Office as all he could think is some flirty demeanour from the teacher. He blushed at the thoughts and covered his face and screamed internally. He knocked on the door and slowly entered the Office, Not forgetting to close the door behind him.

Nightmare looked at Error and smirked softly as he briskly walked to him and grabbed his chin. Error looked at him in a blushing state as his body stiffened up. "What's in your head recently hm? You have been quiet for a while..." He muttered as he took a sip on his strawberry milk.

"...U-uhm... Just about something... or someone..." He blushed softly as he hugged himself and rubbed his neck nervously.

"Hm... really~? Tell me who~" He purred as his face went closer to Error's face as he slowly pushed Error to the wall. He smirked as he had pinned him to the wall so he can't escape from his question.

"I-I uh... I-it's actually uhh w-wrong and um *cough cough* I-I know... uh... that... u-um..." Ertot stuttered as he blushed heavily, couldn't talk at all when his own crush was in front of him and was way too close to him. "I-I love... um... nnhh... uh..."

"Just spill it out before I take your first kiss~" Nightmare purred as his hand caressed Error's cheeks gently as he licked his neck. He knew exactly the answer but he decided to keep it for himself. He know it's inappropriate to read Error's diary book and he knew that Error fell in love with him.

"Uhm..." Error's face flushed deeply but he just jumped at Nightmare and hugged him tightly, Kissing him deeply while Nightmare smirked and kissed him back, Pulling him closer. In a distance, Ink and Dream grinned widely as they watched through the slightly gap from the door lock.

What if... There's continuation Hanahaki Disease 3?

Reader : PLEASE MAKE CONTINUATION OF HANAHAKI DISEASE! PART 2!

Author : OoF- Oki- But angst >:D

Reader : WHUAAAA SO SAD- I'M FLOODING MY HOUSE!
Reader : OOF MY HEARTTTTT
Reader : WHERE'S THE INVISSIBLE ONIONS!?

Reader : PLEASE MAKE PART 3 OF HANAHAKI DISEASE!

Author : No. I apologize but Error is dead and I had tried many version or possible way to revive him but nah. It will be a long ass chapter and sad... SO I DECIDED A PLOT TWIST! Inspired from a webtoon- forget the name... It's about if someone died and the master cat gave them a second chance of life cause he got 9 lives. The dead person will be alive but every sunset till 6 A.M in the morning he will turn into cat. I forget the name- so... uh... bare with me xD

Error is a cat. Not a neko.
Nightmare is a submissive skeleton with Cross.

Nightmare sighed as he was really stressed out because his best friend, Error had died in front of his eyes. He was in guilt for not having to save him and the most important is he didn't love Error more than friends. He loved Error as a best friend that support him but he didn't expect Error loved him more than that.

The most horrible thing is Error died because he had sacrificed himself for Nightmare. He pushed Nightmare closer to Cross and let Error to suffer alone while himself was happy with Cross. He had let his best friend suffer through his pain alone. He was blaming himself for that because he supposed to know that Error loves him so he could at least talk with him out instead of letting him suffer.

Error was a nice person for being able to give Nightmare happiness and healed him from his Hanahaki disease. He couldn't bare remembering how nice Error to him and how he make him happy. He deserved more than his death, He needed Error to be here with him again. But life only happened once and he will just reborn as different living beings.

Nightmare was so deep in thoughts till  he heard s soft meow from a box in front of his house. He had been seeing the box for 2 days and he thought someone might drop it and come back to grab it. He also saw the box is shaking and letting out some weird sounds, But he didn't bother to open that.

Nightmare sighed and slowly walked to the box and picked it up, Carrying it inside his house. He grabbed a scissor as he cut the duck tape and slowly opened the box. Something black jumped out from the box and landed on Nightmare's chest. Nightmare was shocked and saw a fluffy cute cat in front of him.

"HISSSSS!" The cat hissed as it raised its tail in defence as it stayed as tall and aggressive when it realized that wasn't its owner. Its owner was a skeleton with blue scarf, Not a skeleton with purple outfit. It scratched at Nightmare clothes and clawed on his face aggressively as he let out a growl.

Nightmare yelped as he pushed the cat away from him and felt the blood starts tricking from his face. "BAD CAT!" He growled as he winced softy, taking a tissue and wiped some bloods off. He walked away from it as he opened the fridge and grabbed a fish. He slowly walked back to ot and started approaching the black cat.

The cat looked at Nightmare and back to the fish. The cat was wearing No. collar and had unique red mixed with blue eyes and got red paws. It slowly walked to Nightmare, Eyeing him warily. It sniffed on his nail and put a paw on his hand to make sure its safe. Nightmare didn't move at all but just waited patiently.

It slowly took the fish and spit it on the floor. It jumped on the fish happily as it started eating the fish, It has been two days he eat anything. Nightmare smiled softly as he slowly patted the cat but earning a growl, Thinking Nightmare will steal its food. Nightmare sighed and just let the cat eats the food and stop patting it cause it will scratch his hands again.

"Looks like Error..." Nightmare muttered as he smiled softly. Once the cat finished eating, He scooped the cat and patted it gently. He made sure to hold it properly and rubbed under his jaw slowly. He smiled softly as the cat just nuzzled into his chest while letting out soft responses like purring contently.

"I will name you Error. Teehee~!" Nightmare giggled as he booped its nose.

"Welcome to the family..."