Filou had the name of Mini and he was very mini then but I thought when he grows up it would be not ok -the other boys would laugh at him
I first thought of Minou which is french for pussycat (female would be Minouche) but then someone came up with Filou and that's purrfect for his character.

Tigris was Blacky but he was not black but striped. But I didn't want to simply call him Tiger or Tigger because Filou would then look down on him. So I chose Tigris -because then Tigris sounded to me like Thousend and One night.