Work Text:
Roy Mustang had never expected to have the second place position when it came to Riza's love and he definitely hadn't expected that first place would be taken by a dog.
He had always liked dogs, thought of them as animals who were loyal and obedient, he had once even theorized that if it was possible to teach them to hold a weapon they would be the perfect subordinates, but it only took a few weeks of living with Riza for the rivalry between him and Black Hayate to emerge.
Riza of course assured him that that wasn't the case and that it was the dumbest idea she'd ever heard from him, and that really meant something. And that she really couldn’t believe he was jealous of a dog.
But Roy couldn't help but notice that when she got home the first thing she did was give him a pat behind the ear and when she woke up to put food and water in his bowls, and when Roy asked if he would also receive breakfast in bed, Riza told him to stop being lazy and go prepare something himself.
But the rivalry only became official when he and Riza were watching a movie on the sofa. Black Hayate jumped and settled between them and when Roy reached out to push him, the dog looked at Riza with a look full of what Roy knew to be false innocence, which made Riza look at Roy in a way that seemed to say : I-have-guns-hidden-in-every-room-of-the-house-so-stop-being-mean-to-my-dog and so he did. And Roy could feel the satisfaction this brought to Black Hayate and at that moment he thought: You won the battle Hayate, but not the war.