"Huh?!"
Lin Mo froze on the spot.
How did Lisa know he had done those indescribable things with them?
And how did she know he had just met Rosalyne?!
Wasn't she supposed to be drinking at the tavern the whole time?!
Lisa looked at Lin Mo's utterly baffled expression and smiled with interest.
"Little brother, are you wondering how your big sister knows about what you were doing with them in private?"
"Why… why do you know?" Lin Mo asked instinctively.
"Of course it's because you couldn't even get out of bed last night~" Lisa said lazily.
"Only Eula came out of your bedroom and joined us to collect dragon tears and head to Starsnatch Cliff for the mission."
"But before that, Eula had stayed alone with you in your room for several hours."
"And with such a lovely moonlit night, what kind of wonderful things might happen… well, that's easy enough to guess, isn't it~?"
Lisa's deductions matched the truth perfectly.
Lin Mo knew it really was suspicious.
And since Lisa already knew about his relationship with Eula, guessing what had happened wasn't difficult.
But what he couldn't understand was—
How did she know about Rosalyne too?
"Let me guess," Lisa said with a knowing smile, meeting his questioning gaze before he could speak.
"You want to ask how I knew about your… tender moments with Rosalyne as well?"
"Yes. How?" Lin Mo asked, confused.
Lisa smiled and explained.
"Not long after we arrived at the tavern, a report came in from the Knights. They said a dazzling fire moth had appeared in Mondstadt."
"At first, Jean wanted to cancel the celebration banquet and investigate personally."
"But then Venti showed up."
"He told us the fire moth was the Fatui's Lady—the Crimson Witch, Rosalyne."
"And he said you'd already handled the situation, so there was no need for us to worry."
Lisa's explanation made everything click for Lin Mo.
He had wondered earlier why, after being absent from the tavern for two full hours, no one from the Knights had come looking for him.
So Venti had been covering for him in secret.
Still, Lin Mo couldn't help asking, "But… how did you guess that something definitely happened between me and her?"
"It's written all over your face," Lisa said, letting out a helpless chuckle.
As she spoke, she reached into the small pouch at her waist, pulled out a mirror, and handed it to him.
"Written on my face?"
Lin Mo frowned, puzzled.
But the instant he looked into the mirror—
He understood everything.
The reflection staring back at him looked utterly drained.
His face was pale, his expression exhausted.
And most importantly—
On his neck.
On his cheek.
There were two bright red lipstick marks!
They were unmistakable traces of intimacy—
Left behind when Rosalyne had clung to him earlier.
Lin Mo felt an overwhelming surge of relief that Eula and Jean were already drunk.
If they had noticed this…
There would have been no way to explain it.
"Little brother…" Lisa said earnestly.
"You really need to learn some restraint."
"I—I have been restrained!" Lin Mo protested seriously.
He really had been!
The problem wasn't him at all—
It was Eula and Rosalyne!
No normal human being could withstand them!
This absolutely wasn't because he was weak!
"All right, all right~" Lisa waved her hand dismissively.
"That's your own problem. Your sister was just offering a little reminder~"
She paused, then changed the subject.
"So, why did you want to invite your sister into your room?"
Lin Mo's gaze hardened with determination.
"Lisa, I want to help you resolve the hidden danger in your body."
"…Don't tell me your method involves doing that?" Lisa asked, raising an eyebrow.
"No!!" Lin Mo denied it instantly.
Where did she even get that idea?!
He quickly explained.
"I possess Khaenri'ahn bio-alchemy."
"One of its incomplete techniques is called the 'Super Heart.'"
"For example, my own heart was modified into a Super Heart by Rhinedottir back then."
"If we could perform the same modification on you…"
"The life force you've burned through as a witch could be restored."
"And in the future, you'd be able to wield your witch's power without any worries at all."
…
As she listened, the shock in Lisa's beautiful eyes grew deeper and deeper.
"So…" she said slowly,
"You're proposing a heart modification surgery for me?"
"Yes—but also no," Lin Mo shook his head.
"I've only mastered about seventy to eighty percent of this technique. It's still incomplete."
"If I worked on it alone, I might eventually perfect it, but it would take time."
"However… with your help, I believe we can speed things up significantly."
…
"Come," Lisa said after a moment, her usual lazy demeanor completely gone.
"Let's talk about this in the bedroom."
The technology Lin Mo described had completely captured her attention.
…..
They talked all night.
Lin Mo told Lisa everything—
From his past with Rhinedottir to the very beginning, leaving nothing out.
Lisa, in turn, came to fully understand Lin Mo's current level of bio-alchemy.
Even though it wasn't black-soil alchemy, her intelligence alone was more than enough.
With Lin Mo sharing everything he knew without reservation,
Lisa mastered all of his bio-alchemy theories in a single night.
They were only theories, of course.
But with Lisa's intellect, it was more than sufficient for her to collaborate with Lin Mo on perfecting the Super Heart.
….
…..
Over the next half month,
Lin Mo and Lisa secluded themselves in Mondstadt's research facility, fully devoted to their work.
During that time, Klee, Eula, Jean, and Noelle all tried to visit Lin Mo.
Lisa turned every one of them away.
No interruptions were allowed.
She understood the enormous significance of this technology.
If fully perfected, Mondstadt could mass-produce knights with Super Hearts.
Mondstadt would secure absolute military dominance across Teyvat.
Compared to this, the Fatui's life-draining elemental armaments would be nothing more than child's play.
Another half month passed.
The technology achieved a breakthrough.
Lin Mo was now confident that the technique he and Lisa had perfected together was nearly identical to the one Rhinedottir once possessed.
But whether it could be flawlessly reproduced—
That required testing.
Lin Mo couldn't risk any oversight causing irreversible consequences.
After all, this technology would first be used on Lisa and Rosalyne.
If anything went wrong…
He would lose them forever.
That was an outcome Lin Mo could never accept.
So, together, he and Lisa decided—
To conduct an animal experiment first.
…
The experiment was a success.
After the surgery, the small black dog showed no adverse reactions and remained perfectly healthy.
Watching the dog, Lisa couldn't help but ask,
"But how do we know its vitality is truly stronger than before?"
"That's simple."
Lin Mo smiled as he picked up a Favonius sword from nearby.
At the same time, he held out his Dull Blade toward the little black dog's mouth.
"Here, Xiao Hei—hold the sword and fight me."
"Woof!"
The little black dog responded eagerly.
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T/N:
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