These are honestly two of my favorite characters <3
Gianni is dirty and gristly and old and loves the young, beautiful Andries tremendously, but Andries repeatedly uses him and breaks his heart. It's so sad :< However, Gianni eventually realizes that it's all an elaborate game of hard to get. Andries adores him. They don't really get a traditional happy ending, but at least they are happy together.
They aren't cats, but if they were animals they'd both totally be cats. It fits them perfectly.