Two hours after the last one, I came up with this while shopping for vegetables.
Don't Neglect Your Pet 2: She Followed Me Home, Can I Keep Her?
Knives gave his brother a cool, superior look over his newspaper. He sighed, and realised his brother would want to keep it in spite of the arguments. "They're such short-lived creatures, I don't know why you'd want one. But remember, dear brother, do not neglect your pet―"
"I know how to care for her," Vash pouted, staring at the little black cat washing her back on the windowsill, "and y'know, she's been following me around for years."
"Remember that hygiene is of paramount importance," Knives continued, smoothly ignoring his brother, "and you'll need to keep her well fed and happy to keep her from straying."
"Stop talking about me like that!" Meryl screamed.
I think this was floating round my head after reading fics where Knives calls Meryl Vash's "pet" : )