The highly anticipated cola-in-the-face scene didn't unfold as smoothly as Ellina had planned.

The reason for the failure wasn't that Ron cleverly sensed something amiss, nor that Harry Potter mustered the courage to expose the prank.

In the early nineties, carbonated beverages simply weren't saturated with enough gas. Plus, Ellina overestimated the pure-blood wizards' manual dexterity. Ron, who had never seen a twist-off cola bottle cap before, spent a good five or six minutes figuring out the correct way to open it.

As a result, the surging bubbles had already calmed down quite a bit. The cola that spilled from the bottle only managed to reach Ron's upper shirt before losing its momentum and mostly landed in his shirt pocket.

*Squeak squeak squeak…*

As the cola splashed, Ron's shirt pocket suddenly began to squirm, emitting a series of panicked squeaks.

"Oh! My God, Scabbers…"

Ron was startled by the sudden surge of cola, and quickly moved the bottle away from himself. He frantically reached into his inner shirt pocket and pulled out a chubby grey rat, placed it on his lap, and looked up at the two around him, quickly explaining.

"This is Scabbers, he’s useless, sleeps all day. Percy got made a prefect, and Dad bought him an owl, they couldn't afford – I mean, they just gave me the rat."

After a brief explanation, Ron's ears turned slightly red. He turned his head and looked at the silver-haired little girl sitting across from him with a mixture of confusion and hurt in his eyes, changing the subject.

"What happened, it suddenly just…"

"Oh no, I forgot to remind you…"

Before Ron could finish his question, Ellina slapped her forehead and let out an exaggerated exclamation, her face filled with regret. She proactively spoke up, her tone full of self-reproach.

"Ron, you were just too slow at opening the bottle. The magical substances I stirred up in the drink reawakened. You should have shaken it harder before opening it."

"Magical substances?"

Ron looked up, confused, at the cola bottle in his hand, and frowned. "But, didn't you just say it was a Muggle drink?"

"Well, it's like how the magical world also eats ordinary potatoes. Isn't it normal for Muggles to collect some magical substances and use them as drinks?"

Ellina shrugged her shoulders, explaining in a serious manner. "You don't think any ordinary liquid can flow upwards like that, do you? Listen closely, and you can hear the sizzling sounds those magical substances are making inside each drop of liquid."

"Is that so?"

Hearing Ellina's explanation, Ron hesitantly put his ear close to the cola bottle. Sure enough, he heard countless tiny crackling and sizzling sounds, and his face showed even more conviction.

Just then, a timid voice came from next to Ron.

"But, Miss Ellina. If I remember correctly, cola won't spray out unless you shake it."

Harry Potter, who had been watching from the sidelines the whole time, finally couldn't hold it in anymore. He raised his hand – although he didn't know why he was raising his hand, he gathered his courage and interrupted Ellina.

"Eh? Is that so…"

Ron looked suspiciously at Harry, who had a simple and earnest expression, and then at Ellina, whose face was filled with wisdom and confidence, and asked uncertainly.

Huh?!

How dare you ruin my show?!

The smile on the silver-haired little girl's face froze, her face darkened, and she glared fiercely at Harry Potter sitting in the corner opposite her, letting out a displeased hum.

Ellina raised her chin slightly, stood up with her arms crossed, pointed her finger at the *Magical Drafts and Potions* in Harry's hand, and slowly said in Lucius Malfoy's arrogant tone.

"Mr. Harry Potter, the world is far more wonderful than you imagine. Do you know why cola produces bubbles? Do you know what magical substances it contains?"

Faced with the aggressive Ellina, Harry Potter shrank back nervously, shook his head, and honestly replied, "Sorry, I don't know."

"Hmm, then you certainly don't know about the ubiquitous dihydrogen monoxide, and the terrible substance called Co2, do you?"

Ellina crossed her arms and looked down at the pitiful Harry Potter, her tone becoming even more mysterious.

"Sorry, I don't know either." Harry shook his head again.

Sure enough, a gleam flashed in Ellina's eyes. Just as she thought, even though he had lived in the Muggle world before, Harry Potter, who had just graduated from elementary school, was as clueless about chemistry as other wizards.

After getting a satisfactory answer, a playful smile appeared on Ellina's lips – dare to ruin my show? I'll mess you up so badly, I'll be sorry for my nine years of compulsory education in my previous life. By the way, I'll take this as a practice run for some actions at Hogwarts later.

Ellina cleared her throat, her face turned serious, and she raised her finger, speaking slowly, as if she was telling some important ancient secret.

"Co2 is an extremely terrible substance, its danger is something even Muggles can clearly recognize. Ancient humans called it death gas. It can extinguish flames, it can suffocate people, people even believe that one day it can destroy the entire civilization on the ground."

Glancing at the two boys who were listening attentively, the silver-haired little girl paused, lowered her voice, and continued to narrate mysteriously.

"As for dihydrogen monoxide, it is a colorless, odorless, and tasteless magical substance. It takes the lives of tens of thousands of people every year. According to incomplete statistics, the mortality rate caused by inhaling dihydrogen monoxide liquid through the respiratory tract ranks among the top ten in human unnatural deaths. Moreover, dihydrogen monoxide is a necessary condition for the formation of most diseases. People addicted to this substance will die if they leave it for 168 hours…"

As time passed, the atmosphere in the compartment became more and more solemn. Harry and Ron's faces were filled with tension, and even their breathing was very low, listening intently to Ellina's little class.

After all, what Ellina said was reasonable, logically rigorous, and sounded very convincing. In addition, the girl had always shown an undeniable aura, so Harry and Ron couldn't help but believe it.

"But, Sister Ellina."

Ron swallowed hard, raised his hand, and after getting Ellina's consent, asked in a low voice, "What do these two terrible magical substances have to do with this cola?"

Ellina nodded in satisfaction, tapped the transparent cola bottle with her fingertip, and smiled slightly.

"Good question, because… the main components of this black liquid are actually dihydrogen monoxide and Co2. You will learn about this in more advanced potions courses when you grow up. Remember not to show it to outsiders, especially professors, in advance. Learning high-grade potions knowledge too early is forbidden."

After glancing at Harry Potter and Ron Weasley, who had been completely led astray, with a serious expression on their faces, indicating that they would never spread the word, Ellina narrowed her eyes, looked at Harry and Ron, and earnestly summarized again.

"Please note that you are about to become mature wizards. Don't waste magical drinks in the Muggle way. The correct way to drink this substance in the magical world is to shake it before drinking it. When you can suppress the riots caused by cola with your own magic, it means you have become a great wizard like Dumbledore. Understand?"

"Yes! We will try our best. Thank you!"

The duo nodded in unison, their eyes filled with hope and determination.

"You're welcome, we are classmates, we are friends. This is what should be."

Ellina shook her head with a light smile.

Youth is so enviable… Although it's a bit tiring, it really brings a double dose of joy after helping others solve their doubts – who made her such a kind-hearted, helpful little fairy, no, little witch?

Returning to her seat, Ellina opened *Standard Book of Spells, Grade 1*, ready to continue learning spells, when a low rumble suddenly came from her stomach.

*Goo~*

Why am I so hungry all of a sudden?

The girl looked out the window, the fields and pastures flashed past her eyes – while they were talking, the train had already left London.

It turned out that so much time had passed unconsciously. It was almost lunchtime, which meant that the snack trolley should be coming soon.

Ellina looked up, her eyes eagerly looking at Harry, who was concentrating on previewing the Potions textbook. She swallowed imperceptibly. Such an opportunity to eat at someone else's expense must not be missed. Hmm… Let's just consider it as Ellina's tuition fee for the chemistry class just now.

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Sorry, these two chapters may be a little bit filler. On the one hand, it's impossible to have high-point plots all the time, on the other hand, the later back-to-school plot is really too important, and it needs more time to think about it carefully.

ps: I went to buy gifts for everyone today!! ~~I bought a lot of HP peripherals~ I'll slowly give them to you later~~

I am a guilty Scottish round-faced skinny chicken, I feel like I haven't written well recently, I don't dare to ask for recommendation tickets to feed, I am self-fasting as a punishment, *ying ying ying goo goo goo~~~*