If Manchee isn't your favorite character by the end of the book, well, then—it's your business, and we'll totally still be your friends, but we also don't really get it. Because it's not like you even have to be an animal person—he can talk. Sort of. Or his thoughts can. And who doesn't like a super communicative dog? Not us, that's for sure.
Manchee is Todd's lovable and trusty sidekick. Even though Todd makes it very clear how he feels about this at first: "I never said I wanted a dog […] but oh, no, happy birthday, Todd, here's a brand new puppy, Todd, and even tho you don't want him even though you never asked for him, guess who has to feed him and train him and wash him" (1.6)… Okay, that's enough. You get the point: poor Manchee.
We have to give the dog some credit—Todd's moody behavior isn't a walk in the park for man or beast. At first, all we seem to hear is Todd complaining about this little guy trailing at his heels.
But it turns out pretty quickly that without Manchee, Todd would be a goner many times over. For example, Todd thinks about returning to Prentisstown after Ben helps him escape, but Manchee chimes in with "Promised, Todd" (6.12), holding our main man to his word and, in the process, his path.
And let us not do the pup injustice by forgetting about his heroic demise. In an act of pure loyalty, Manchee gives up his life so that Todd can save Viola. It's an act of true loyalty (as dogs are known for doing), and when we picture Todd looking to the shore of the river and hearing "a scream and a cut-off yelp that tears my heart in two forever and ever" (31.196), we shed a tear. For all he rags on Manchee, that dog really is this young man's best friend. Aw.