Let me cite Oxford’s definition, which, for the most part, I agree with:
friend — a person whom one knows and with whom one has a bond of mutual affection, typically exclusive of sexual or family relations.
However, friendship is not just about two people knowing and feeling affection for one another; it also entails profound acceptance of one another’s flaws and weaknesses. Moreover, I believe it possible for people who are vastly different and diametrically opposed—even enemies—to become friends. Admittedly, I am an optimist.
Keep in mind, I suggested that I would be interested in seeing Jean and Emma’s relationship evolve into a friendship, which ideally would take time (and nuance) to develop. Nevertheless, their shared history has all of the ingredients that would make for a complex and realistic friendship.