My two female dumbo rats were also bought from pets at home and are 1 and a half, they were extremely shy at first and hated coming near me, mine have bitten twice only and are now extremely loving and friendly. Mine are still slightly shy and are sometimes reluctant to be held or stroked by new people. I found that by sitting by them for 10-15 minutes a day really helps, they soon got used to me and now i often find them waiting for me, it really is just a case of them starting to recognise you/your scent, don't make any sudden noises or movements and talk softly to them. Cleaning out is also bonding time, talk to them and if your feeling brave stroke one finger from their shoulder blades down, they quite like this. Hope I could help. x