If Harry Potter is searching for one thing in his life, it's probably family. And in a lot of ways he's found family – through his friends, through the Weasleys, and now through his father's old buds. Family is about much more than just blood ties here – it's about qualities like loyalty and love. Sirius sums up this theme best when he's interrogating Peter Pettigrew: family are people that you sacrifice and even die for, with the knowledge that they would do the same for you. With this, family ultimately boils down to trust. For example, trust supersedes things like the sibling rivalries and funny interactions we see between the Weasleys, who are probably the best representative of the theme of family in the Prisoner of Azkaban. And finally, above all else, family is about choice. Characters here choose to be or not to be families regardless of whether actual blood ties exist.