Dora eats islands. If she doesn't, she'll starve. Who knows why? All we know is that she refuses to eat anything else. Perhaps the nutritional value of these islands is what gives Dora the strength she needs to open jawbreakers with her head. Dora's language, Insulăvoric, is one of the most difficult languages to pick up.
Dora really, really dislikes David and tried permanently killing him many times. Alas, the recovery do centres always bring him back.