New pet rat. At least this one has domesticated genes in it. The same thing happened to me many years ago but it was an albino red eyed rat that decided to hang around where I used to clean the bird cages, he would scavenge the leftover bird seed. It was easy to catch him with some sunflower seeds placed in the cage. I ended up keeping him for a good two years then he finally developed a tumor and bit the dust. I always wonder if it was one of those strange medical cancer rats they use for testing that escaped out of a lab.