A single Compy is never an issue. Due to there curious nature of humans they'll walk right up to you and observe you without hostility. But after they see you they will send out a call to nearby Campus beckoning them. Once another Compy is close enough to get a pack bonus they loose there neutral mentality and the pack mind takes over and they become hostile to beware of multiple Compys.
Absolutely love these little gremlins. They like to come ip to you and stare at you for a moment, then attack when the pack is assembled. THEY ONLY EAT REALLY QUALITY MEAT! Also, the babies are, like, microscopic, so I’ve had several cases of one escaling out the door and never seeing it again (then getting a “Coraline, Lv. 6 (Compy) died!” notice a few minutes later :(), so if you must breed them, make sure you have TONS of prime meat (which spoils VERY FAST) and make sure the babies stay in a secure location because they are FAST. My favorite thing to do is have a pack of, like, 20 folowing me around and watch as they take down a Raptor nearly effortlessly. Hilarious (also, VENGEANCE >:)).
Although their small stats may make you heavily underestimate them, don't be fooled. These little guys rely on confusing you, and are very small and hard to hit. In high leveled groups with lots of members, they can be extremely deadly early game. For dealing with the annoying groups, just use a torch. If you cannot beat them, and they are overpowering you, I can help. A strategy I've found works is probing (default key X) under a large creature with a neutral temperature, preferably a herbivore with a large hitbox on its body and attacks (a Triceratops would be perfect). This may result in you being hit, but the Trike will kill off all the Compies, giving you time to run, or collect their spoils.