Since it was publicly known that Mrs. Norris had four kittens, Filch has become almost the most popular person at Hogwarts. Every house wanted to have their house kitty, that's why the number of criminal offenders sunk below all historical records.
Also Filch has, since he became a grandpa, become a totally new person. Loving, we could almost say. With the nail of his little finger he poked out from in between nasal hair a very delicious and juicy boogie of military green colour which he shared with Mrs. Norris so she could produce more thick milk.
Stidents gave Mrs. Norris uncomparably better desserts. That's why she decided to exhibit her young in the Great Hall – that was an event that all school participated.
During the schoolyear the kitties were growing up and their characters became crystallized. It was no more doubt about which house shall adopt which kitty:
Hufflepuff: the she-kitty that burried her excrements into salad patch most hardworkingly.
Gryffindor: the tom-kitty who bravely fought against two fat rats at once.
Ravenclaw: the she-kitty who was most ardent explorer and also climbed the roof from where she neededto be solved. Filch, trying to take a shortcut, rushing to help, got stuck in a chimney.
Slytherin: the tom-kitty who brought and displayed his hunting success and was marching up and down the Great Hall during dinner, a half of dead slow-worm in his teeth.