The White Snake Clings to Me

At first, Xi Suxian didn't care much about transmigrating.

She was an honest, sensible girl with a sister who doted on her. All she had to do was study hard and occasionally lend a hand at the pharmacy her sister ran. They weren't rich, but life was comfortable enough, and sometimes she could use what she'd learned to help the sick.

The first person she saved was a dashing young gentleman in white, graceful and handsome. Well versed in the classic romance trope of repaying a life-saving favor with one's hand in marriage, he repeatedly tried to win her over.

Figuring there was no reason to turn down a romance that had practically fallen into her lap, Xi Suxian agreed.

Until...

"My lord, my lord, why have your pupils turned into slits?"

"So I can see you clearly at night, too."

"My lord... why have your teeth gotten so sharp?"

"So you can better savor the sweetness of our amorous kisses."

"My lo... why have you grown a tail?!"

"Now I can use it like a hand and hold you close every moment of the day."

That's a demon, isn't it?!

Xi Suxian fled in a panic. After finally escaping that nightmare, she happened to save another young gentleman, this one in blue, with clear, handsome features and eyes that seemed to ripple with light.

When he brought up the idea of marrying her, she couldn't help telling him about the time she'd nearly promised herself to a demon.

He only interrupted her with a smile. "I know."

Xi Suxian froze.

"He's my older brother."

Xi Suxian was stunned.

"I've been watching you for ages." The young gentleman leaned in close, his words softer than the breeze and as sweet as honey. "Sister-in-law... sister-in-law..."

Premise: What you learn from books is always shallow. To truly understand something, you have to put it into practice.