I can't talk with my rat friends, they just happen to move too fast. I keep clicking beside them. I'm all rat-tled.
And I will be be-rat-ing you larian if you don't change that quickly enough !
Successfully hitting one of those agile rats on the first attempt is definitely something you can cong-rat-ulate yourself for.
Few things here:
1) If you click directly on the rat from a distance, your character will run up to it and open a dialogue the moment it gets into range. This is easier than trying to click near the rat's current location, and then clicking on them again to attempt to chat.
2) More importantly - the rats aren't running from your character with pet pal. They're running from your characters *without* pet pal, who are probably chained to your animal-loving character and following them around everywhere, which in turn is causing the rats to flee from them (and as a result, you). Whenever you see an animal you want to talk with you'll have a much better result by disengaging from the party (sever the link by the portraits) and walk calmly over to the creature - it won't run as long as the rest of the group keeps its distance. Once you've got it talking you can safely bring the rest of your party over.
You are suppose to use cheese to lure the rats. It's in the book "rat extermination." Also, why there's a cheese vendor. If you want to talk to them, use normal cheese to get them to come to you, if you want to exterminate them, use poison cheese.