That's one of the questions that comes up in the latest installment of the webcomic Subnormality, in which a young woman has befriended an ancient Sphinx who occasionally feasts on human flesh. And people won't stop asking her how she can be friends with one of humanity's few predators.
Winston Rowntree wrote and drew the heartbreaking story we featured a few months ago about a time traveler observing a girl with a terminal illness. In the new Subnormality, he returns to two of his regular players: the Sphinx and the Pink-Haired Girl (who often had brown hair; just go with it). Although these two appear in multiple Subnormality strips, you don't need to keep up with the comic to enjoy any particular installment. (You just need to know that in this particular edition of the comic, we see the Pink-Haired Girl at different points in her life with different hair colors.)
It starts with a stranger on a bus asking the Pink-Haired Girl a question: "How can you be friends with that thing?" From there, we see two narratives played out in parallel. One is a typical conversation between the Sphinx and PHG in which PHG airs her insecurities and receives the Sphinx's perspective. The other is a series of conversations that PHG has about the Sphinx, many with people who disapprove of their friendship. She has to confront the question: is she a terrible person for making nice with a human-eater?
Like so many Subnormality comics, it gets into the existential questions of humanity. How do we deal with the fact that we're inherently conflicted? How do we accept our own hypocrisy without waving it away? And is it ultimately childish to be friends with a monster? Subnormality is notorious for its walls of text and this entry is no exception. But I highly recommend sticking with it. It doesn't feel the need to answer all the questions that it asks and it is, in the end, a very sweet comic.