You gotta word them real carefully. When I got here, I was tawtute human, and I was in a wheelchair. My twin wished me better, and I was! I could walk and run and fight and, I dunno, climb trees, for 14 months and then it stopped working and I had to go back into the wheelchair. Wishes get loopholes, it's their thing. So if you're determined to make a wish, you gotta cover every base you can think of and about 16 you didn't even know existed, or it'll backfire or go wrong or something'll fuck up and you'll be back where you started.
Oh, yeah, I get that. When I first got to Pandora and met Neytiri, she had to spend three months showing me how to behave, what to do and not to do, all kinds of things.