In my book Grimm was doing what he wouldve done for anyone. Whether Allyson was as mean back to da "bitch" wouldnt be known to him but he is gonna just do whatever he believes is right. He is childish and impulsive. :p ERode wins a cookie. :3 Its what Grimm's there for. He'll probably become less of a... Strict wouldn't be the word but not every wrong made by a human would make them lose a finger or other body part.

 His spirit will at least try to lecture him every time he does something she doesn't agree with. But Themis herself was a rather short-tempered judge. He'll get some more popular morals later on probably. Or maybe he'll just murderize more people. *shrugs* The latter is much more entertaining.

Edit: Libra x Merthus foah life