by the way, the behavior of 愛兒 may be explained by the animal's territory instinct.
she knows that, at your 愛兒's home, she is the owner of the home, and thus, can take up anything in her home;
In your friend's home, she knows that she is not the owner, the other boy is. Thus, she surrendered to the other boy.
For the same reason, i once noticed that: my neighbor's dog is scared of the little cat in my house. Because the dog knows that my house is the territory of the little cat, and his territory is another house.