It’s how he worded he’s response when the wolf asked him why he came to visit him in the wolf territory seeing it’s dangerous and the rabbit said “I’m your boyfriend” instead of “you’re my boyfriend”. That simple choice of phrasing shows who is dominant and who is submissive. The “I’m your boyfriend” sounds more dominant as opposed to if he had said “you’re my boyfriend” which sounds more submissive. By that response the other wolves could tell who was the dominate in the relationship, which was the rabbit.
Ohhh, that makes sense now. I was always curious on how they knew, thank you!
And i thought i was overanalizing things-
Chapter 1 page 30 to 31. As soon as Usagi, came into the wolf’s den or something, how did the other wolves know that Wolf kun was bottom? Specially the scene where Wolf kun grabs his bf’s hands and exits out of embarrassment, that’s when the other wolves thought ‘Oh, he’s definitely being done by a rabbit’