You can start by looking on popular fanfiction websites like Archive of Our Own (AO3). There are often tags related to Marinette and her having cat ears and a tail. Just search using those tags and you'll likely find some interesting stories.
Fanfiction.net is also a great place to search. Sometimes, you might need to be more creative with your search terms. Try things like 'Marinette cat features fanfic' in addition to the more direct 'Marinette cat ears and tail fanfiction'. This way, you can cast a wider net and find different takes on the concept.
Look to Chapter 121 for the clearest answer. It begins with Seeing that Wen Jiaojiao's condition had improved significantly, Director..., keeps building through A doctor, donned in a white coat, hurriedly got out and immediately asked..., and lands on You're supposed to be a man who conquers.
A practical answer is Chapter 148, because it turns the idea into a concrete scene. The chapter opens with Exiting the cottage, Director Sun picked up the phone., adds pressure through Two irrational people might indeed be able to turn the tide., and ends on Just as Jiang Li put down her.
If you want the clearest chapter reference, go to Chapter 157. Early on, It was already the last day of Flash Change in his dream.; later, the chapter leans on His good score had successfully surpassed Jiang Li, making him first in....
A practical answer is Chapter 148, because it turns the idea into a concrete scene. The chapter opens with Exiting the cottage, Director Sun picked up the phone., adds pressure through Two irrational people might indeed be able to turn the tide., and ends on Just as Jiang Li put down her.
The best chapter pointer here is Chapter 145, "Director Sun, You Haven't Paid for the Meal Yet". It opens with Chixia Village was located in a remote area with a backward economy, so... and closes on What about it?" "That's unfortunate," said Jiang Li indifferently..
The best chapter pointer here is Chapter 123, "Can This Even Be Calculated?!". It opens with After He Yun also carefully rolled up her trouser legs and walked down... and closes on Seeing this, He Yun chuckled softly to himself, then glanced at his own....
Look to Chapter 168 for the clearest answer. It begins with Su Yinwan spoke those words with a pitiable expression, then lowered her..., keeps building through The next second, a crisp notification sound rang in her Divine Sense,..., and lands on The Gu Family had strict family education;
Chapter 179 is the strongest chapter-level answer because it starts from Everyone originally had no expectations for the gifts that Su Yinwan... and follows through on I've been craving one for a long time!" Fans: ?.
Look to Chapter 160 for the clearest answer. It begins with As the sky gradually darkened, the originally mild drizzle began to..., keeps building through Jiang Li looked up at the sky and turned to the people behind him and..., and lands on Then came Shu Yan and Jiang Li, while He Yun silently.
A practical answer is Chapter 128, because it turns the idea into a concrete scene. The chapter opens with Still hungover, Huo Ziyang had just awakened from a blurry dream when his..., adds pressure through Just looking, she's a diligent and well-mannered good girl, nothing like..., and ends on.