25 years ago my son brought home your basic grey rat from his science class.  Long rat tail, basic gray rat to take care of through the Christmas holidays, we called him Fatso, he became a permit member of our family.  He was very sociable, he was also an escape artist, a regular Houdini.  He would take regular trips outside of his home (his long finger like claws could pick any lock).  He always returned, usually at night, he would nibble on my sons ear, he wanted to be feed & watered.  He was content for a few days and would escape again.  We had Gerbils & Hamsters they never had Fatso's personality, nor were they as clean.   I remember one evening when we had a few friends over, Fatso escaped from his home and came meandering across the great-room floor, I reached down picked him up and put him on my shoulder, he nestled in, my guests were shocked to say the least.   If you want a sociable caged criteria, one who doesn't bite, is clean (he was a lot cleaner that the Hamster or Gerbil)  I suggest you get a basic gray rat.  They love people, are independent & they know where home is.