When we got Lily, she was a puppy and she would 'harrass' Dexter too. He is older and VERY laid back. She was just all over the place, biting and playing non stop. Dexter is patient for the most part, but he does snap at her - never really biting, just making sure she stops by snapping and yelping. We almost got rid of Lily because she was such a handful and didn't think they got along until she reached her first heat. Then Dexter loved her of course. (hahaha) Really, it's just the puppy age that they act like that. Lily is older now and has calmed down a LOT. She still pushes Dexter around some but she is not as bad as she used to be.
It just takes time and a TON of patience ... oh and a very watchful eye. They will eventually get along, but it will take at least a year or so.....
good luck!
