This Russian rat is fairly large and not frightened of cats. Why? It is suggested that the rat is infected with toxoplasmosis. The audio file below explains why rats which normally avoid cats go towards them.
The toxoplasmosis protozoan changes their brain function such that they are attracted by the cat’s scent. In this instance the rat treats the cats with complete disdain. Absolutely no fear and charges into them. The cats scram except for one who is curious but the rat just jumps up at the cat which sees the cat back off.
The Scientific American audio file below explains why this cat may be infected with the toxoplasma gondii protozoan:
The toxoplasma gondii protozoan on a stained slide:
One last point: the cats may be slightly timid. Cats do vary in character. One of the cats is less timid and goes towards the rat to investigate. A bold cat might have attacked the rat. After all there are two players in this scenario: the cats and the rat. The rat is unusually bold and fearless and the cats slightly timid. They are probably surprised at the rat’s behavior.
It should be said that rats do attack young birds and rabbits for example so they can be aggressive. They can also attack children. This means that the rat may not necessarily be infected with toxoplasmosis. He may simply be very bold.