She was smart (and not just for a bird)

Hedwig (and the same could be said of the other owls at Hogwarts – except maybe Pigwidgeon) proved time and time again that she had more smarts than your average snowy owl.

She always knew that a letter addressed to Snuffles was intended for Sirius; and now that we think of it, never even needed an address to be written on an envelope. She was also able to follow more complex instructions, such as ‘keep pecking [Ron and Hermione] till they've written decent-length answers’ in Order of the Phoenix.

She always managed to show up wherever Harry was, even when he had run away from Privet Drive. Harry was something of a homing beacon for Hedwig – and that’s perhaps because they were each other’s home.