Pullo's treatment of Gaia, both when he "punished" her for her treatment of Eirene and then killing her after she saved his life in the fight with Memio, is one of the things that makes this series so great. It forces us to realise that, however many things we have in common with Romans of the 1st century BC, so very, very much of them is just alien to us.

Pullo's treatment of Gaia, his casual, "just business," even light hearted, killing of Cicero and lack of remorse for any of it are jarring to us, having been raised with the cultural imprint of Judeo-Christian ethos. I could list other instances, not just with Pullo, but with many other characters in this series. It still remains the same. They are different from us, and in many ways that we cannot culturally understand. That is why we study Latin and Greek. That is why we study ancient history. That is why we need to just step outside our modern sensibilities and at least consider that there is another way of looking at things--culturally, linguistically and morally.

This is not to say that they are equally valid for now. At that time and in that culture, they were most assuredly valid for that time and culture. We just need to recognise that.