Harry Potter was saved by a mother's love more than once. Harry may not of had his mother but he had a lot of comfort from mother like figures. Whenever Harry needed comfort it was always from a mother figure.
Dog - why can't we be friends? Cat- because, you are a dog, covered in fleas and you pee on everything and lick everything. Do you understand? Dog- no! Cat- I'm clean- your dog! Scout loves cats but they never want to play