On this page of the Assassin's Creed Valhalla Siege of Paris guide, we've provided a description of the Pat the Cats achievement. You get this trophy by petting 4 cats.
You will get this achievement in Evreux. It is a location in the Evresin region, located in the northwestern part of France. There is a fast travel point in this city.
Turn right after reaching the synchronization point - you will see the market. There are 4 cats on it, which follow scripted paths.
There are 4 cats. Try to memorize their coloring: ginger, grey with black stripes, black and white with brown patches.
Two cats often sleep by the stalls on the right side of the market (area marked 1 in the screenshot above). You can wake them up by shooting near them (they will rise up and move a few meters away) or by running into them.
One cat (usually the black one) resides on the left side of the market, near the well (area #2 in the screenshot above).
You will find the last cat (or two) in a locked house, behind a wooden door. You need to smash it with a weapon, preferably a bow, because the cat may be lying right behind the door (#3 in the screenshot above).
Approach a cat to pet it. An option will pop up - have Eivor pick up the cat and start petting the animal.
You can't pet a cat if you have a hood on your head - the cats will be afraid of you.
If you accidentally killed a cat, leave the location for a while, meditate, and then return using fast travel.