Not a rottie but a mix who came to us, she was found in pretty bad shape, skinny, open wounds, we nursed her back to health, I think she is a pit mix, she has bitten but given her condition I felt bad for her, she must have had a rough life so I thought I could work with her. She is a quick learner, has a list of tricks we taught her, but aggressive in everything she does, even play. Possessive about toys. I'm not comfortable with her around my son unsupervised, I don't let her near the baby at all.
Our other dog is a beagle mix.... he has no problems, as sweet as they come.