Justin and Nicodemus may have been friendly, but we all know that not all rats took kindly to Brisby entering their nest.
Rats are a natural predator of mice after all. I'm sure the owl mentioned that to Mrs Brisby before he sent her to them...
Then again, if one of your natural preds suggested you walk into a nest full of more natural preds... >,>
Commissioned by Raksha_Jareth