One popular trope is the 'fish out of water' situation. The OC, being new to Gru's world, has to adapt to all the craziness. Another is the 'enemies to lovers' trope. Maybe at first, Gru sees the OC as a nuisance but then falls for them. And the 'rescue' trope is also common. The OC gets into trouble, and Gru has to save them, which deepens their connection.
In Gru x OC fanfiction, a common trope is the 'secret identity' trope. The OC could have a secret that Gru discovers over time. There's also the 'mentor - mentee' trope where Gru teaches the OC something valuable. For example, how to be a better villain or just how to take care of the minions. The 'found family' trope is also seen, where the OC becomes part of Gru's odd family unit with the minions and the girls.
Some popular tropes include the 'accidental meeting' trope. The OC and Gru meet in a completely unexpected way, like at a fair or during a heist gone wrong. Then there's the 'power imbalance' trope. Since Gru is a powerful villain, there could be a power imbalance between him and the OC at first, which they have to work through. Also, the 'redemption' trope can be used, where Gru's actions towards the OC lead to his own self - redemption.
A practical answer is Chapter 42, because it turns the idea into a concrete scene. The chapter opens with You've all met now, so this game is very simple," Director Sun said., adds pressure through Both trapped and rendered powerless by public opinion., and ends on As the plane hadn't taken off.
The best chapter pointer here is Chapter 55, "I Can Prove Everything Miss Jiang Said Is True!". It opens with Su Yinwan hadn't expected that, in just one day, Jiang Li's reputation had... and closes on He Yun's fans were immediately displeased..
The best chapter pointer here is Chapter 20, "Miss Su, your defense is somewhat clumsy". It opens with Several people turned their heads upon hearing the sound and saw three... and closes on So, he turned and questioned Jiang Li..
A practical answer is Chapter 21, because it turns the idea into a concrete scene. The chapter opens with Jiang Li's clear and logical explanation had everyone stunned in place., adds pressure through Yinwan, don't worry, I won't let you suffer in vain., and ends on But the implications could be.
A practical answer is Chapter 64, because it turns the idea into a concrete scene. The chapter opens with Chixia Village lay in tranquil slumber., adds pressure through Is there really a need to put her down like this?, and ends on He'd been a host for so many years; he was used to it..
Look to Chapter 54 for the clearest answer. It begins with Five minutes later, the people of Chixia Village, who had received the..., keeps building through Leading them was the village chief himself., and lands on She was also polite and friendly, and to top it off, she was good-looking,....
The best chapter pointer here is Chapter 49, "Mysticism Girl Jiang Li". It opens with My phone!!!" Jiang Yan's roar echoed continuously through the mountains in... and closes on Thinking this, Jiang Yan marched forward, pulled Jiang Li down from her....
If you want the clearest chapter reference, go to Chapter 39. Early on, Qi Tianyu had been looking forward to watching Jiang Li's drama unfold.; later, the chapter leans on But to his surprise, Wen Jiaojiao, who seemed to possess some strength,....
If you want the clearest chapter reference, go to Chapter 81. Early on, Qi Tianyu, who chose curry beef rice, received a piece of curry and a...; later, the chapter leans on Shu Yan was relatively lucky, she got a bundle of noodles and a bag of....
A practical answer is Chapter 56, because it turns the idea into a concrete scene. The chapter opens with Lei Shen originally had no idea about the trending topics on Weibo., adds pressure through So, bring it on, Blackie, starting today, I am Jiang Li's diehard fan!, and ends on At this moment.