They're best friends and they may treat each other badly at times, but other times, they get along really well.
They never seem to hurt each other in a way that could ruin their friendship, and all they really do is insult, which could possibly be their way of hiding their feelings. They're best friends, and they bicker, but they also insult each other and act like they're not friends.
Typically, when there are three best friends, the two that bicker and fight the most are the ones that end up together.
(Seddie, Loliver, Lucaya, Romione, Channy, etc.) Olive teases Fletcher a lot, however this may just be her way of showing her feelings about him.
Their relationship is complicated because they can go from friends to not friends in a drop of a hat.
Sometimes Olive is kind and caring towards him and other times she's mean and violent towards him.
They do seem to be good friends and get along with each other most of the time.