The thing that sums up my issue with Spider in the Avatar movies is that he repeatedly inserts himself in a culture that does not want him there. Playing with the Sully kids is one thing because playing with the kids around your age is understandable. Except the Na'vi haven't adopted him and while they aren't usually outwardly cruel (with the exception of Neytiri on occasion), they obviously don't like the kid hanging around so much. Spider is that kid that stays way past his welcome and invites himself to family functions, you know?
Which is why it bothers me that he basically cosplays as Na'vi. He paints his skin and makes a loincloth that is supposed to look Na'vi but really isn't. The people at the lab raised him and I have no doubt that he has human looking clothes and he doesn't wear them. It really gives 'white kid who wears feathers and a costume to the powwow'. Being friends with someone from a specific culture doesn't entitle you to be a part of that culture especially when the adults of that culture don't want you there. Even Jake, who is the most sympathetic to Spider, doesn't really seem to like him that much and initially describes him as a 'stray cat' who sticks to his kids. He cares that the Sky People having Spider puts his family in danger and makes his kids upset. You can't really blame him for not putting his children in danger for a child who isn't his. No Na'vi adopted Spider. While harsh in the moment, Neytiri saying that Spider isn't a part of her family is not wrong. He's not. You can't blame the kid for who he's related to or how he was born, but the way he acts is the bit that bothers me.
























