One popular 'submissive creature' themed Harry Potter fanfic might be 'The House - Elf's Tale'. It delves into the life of a house - elf in the wizarding world and shows their submissive nature in a detailed and somewhat sympathetic way. However, there are not a huge number of fanfics that specifically focus on this theme as it can be a bit of a niche area within the Harry Potter fanfic universe.
There's a fanfic I once heard about where it explored the submissive nature of some of the more timid magical creatures in Hogwarts' grounds. It was more of an ensemble piece that included creatures like the Nifflers. The author was really good at showing how these creatures interacted with the students and faculty in a way that emphasized their submissive qualities. But it's quite hard to find as it was a relatively old fanfic.
The best chapter pointer here is Chapter 24, "The Cause of Jiang Shixu's Illness". It opens with Not only that, even the non-mainstream photos she had previously posted on... and closes on Shi Xu rarely feels like going out, so that's nice." Aware that he....
Chapter 14 is the strongest chapter-level answer because it starts from Lin Manru had a rare good night's sleep. and follows through on But clearly, Lin Manru was unable to accept that her delicate daughter had....
If you want the clearest chapter reference, go to Chapter 11. Early on, After a meeting, Shang Shaojing pinched the bridge of his nose, tired, and...; later, the chapter leans on How is it going with the Jiang Family?" The assistant looked troubled and....
Chapter 532, "Little Lolita Beats Up Jungle Python?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Outside the cave, the four people grasped their weapons tightly and...
Chapter 778, "The Gift of Being a Director", is the clearest early answer because it turns Shen Lan's situation into a concrete plot event. The chapter turns that into something concrete by moving from Shiguang, I really misjudged you, you're actually this kind of...
Look to Chapter 31 for the clearest answer. It begins with Before Shen Lan had reached the backyard, she already heard the sounds of..., keeps building through Facing the freshly risen morning sun, she noticed at a glance the girl..., and lands on After staying in the study and reading for another.
Chapter 893, "From today onwards, he is my half-brother from another father and mother!", is the clearest early answer because the buildup finally cashes out in a real clash. The chapter gives readers a real answer by opening on Jiang Yan still had unwavering faith in Daniu's character.
Chapter 781, "Master, accept my bow!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Not only were the criminals curious, but so were the others.
Chapter 756, "Birthday Banquet", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. The chapter turns that into something concrete by moving from On the day of the birthday celebration, the Jiang Family got up early.
Chapter 826, "Deadlock", is the clearest early answer because the violence around Shuiyun Temple becomes final instead of hypothetical.