We have only seen Petunia Dursley through the perspective of one person. We don't know her motives, only what she says. But if she hated Harry so much, why did she take him in?
Fluffy has a slight problem. His little Rin-chan is all grown up and catching the eyes of a few boys. Sesshy's decided that it is time to give the girl "the talk".
All the evil dudes in HFIL are forced to do community service on Earth. Dende, being the evil little god that he is, makes that service be substitute teaching at Orange Star High. I'm so cruel to my Gohan-kun. ^-^