I have two rats. One boy (peter) and one girl (fry). I only had a girl and my friend kinda just abandoned his rat so I kept the boy. They are about the same age, I guess. Fry is a little bigger than Peter. Anyways, I had them for about 3-5 days now. They have a pretty big cage. Not too crowded. Plenty of food and water. I just wanna know how to gain their trust... I spend about 20-30 minutes a day. And at random times i'll try petting them with my fingers. At first they'd run away but now they sniff my finger when i'm petting them and sometimes they'd kinda nibble at me (why?)