Today I went to the animal shelter again. This is Kees (pronounce 'case'):
Kees is an ex-male, en only 4.5 months old. He's been castrated a week ago, which means he can still impregnate Annabel during the coming week. Therefore I borrowed an extra cage from the shelter and I will keep Annabel and Kees separated for the coming 1.5 week. This gives them the time to get used to each other more slowly before I put them together. They are quite interested in each other:
Annabel has licked Kees already (but she also has scratched him with her paws), and Kees makes little 'gn gn' noises to show her he likes her.