I had pet rats in college. They are very intelligent and can be very affectionate. If you get them young they get accustomed to you and incidents of biting are reduced (you may still get bit if you startle them or hurt them). I always had two so they could keep each other company. Their diets are very exact though and you should feed them the recommended food pellets. Their life expectancies are only around 2 years though so if you get attached be ready for it.