Cersei had never disliked cats, but she had never been overly fond of them either. So when Margaery had given Tommen three black kittens she was neither pleased nor displeased. She hoped that perhaps these kittens would grow up to prove their usefulness by catching mice. Indeed they had.
Well, at least two of them had. Boots and Lady Whiskers had caught more than their fair share of mice and certainly earned their place in the Red Keep. Ser Pounce though ironically, given his name, had not. He certainly wasn't starving though, no he was the biggest of the three cats. Cersei strongly suspected Tommen was giving him more than just scraps of food. She did not approve of that. Ser Pounce needed to learn to fend for himself. If he couldn't, then she reasoned that perhaps nature should just take its course.
So when she'd heard that Tommen had requested fish tarts for his afternoon snake four days in a row, she was none too surprised.
She made her way to Tommen's chambers to scold him. He would already be at his lessons by the time she arrived to scold him, but she could wait.
Arriving in Tommen's chambers she sat down on his bed and waited. The cats were seemingly nowhere to be found. 'Good, at least he's obeyed me about them not staying in here while he is out.' No sooner did she finish this train of thought then she spotted a pure black cat on the window sill eating what appeared to be fish tarts. As Boots had white paws and Lady Whiskers had some white on her tail and face she realized this was Ser Pounce.
Once he finished his food, he jumped up onto the bed. She shoved him off. He jumped back on. After a few more tries of this, she gave up. Ser Pounce then made his way onto her lap. Cersei rolled her eyes, but after some time began to absentmindedly pet the cat. After some time, he began to purr.
Shortly later, Cersei moved to leave. She had decided she wouldn't let on that she knew about the fish tarts or any other food Tommen might be having sent for Ser Pounce.