"The greatest thing you'll ever learn is just to love and be loved in return." - Eden Ahbez, Nature Boy (song, recorded by Nat King Cole)
White Fang by Jack London (252pp) is one of my personal all time favorite books.
It is the story of a 3/4 wolf, 1/4 dog that grew up as a loner and fighter. Named by Indian masters 'White Fang', he first learned to use his fangs in his own defense, then in the defense of his masters, and finally in offense.
White Fang is sold to a man who sets him against other dogs for entertainment. He was beaten and goaded and mistreated, and he grew to hate the humans that crowded around his cage... and he took it out on the dogs that he met.
But then White fang is rescued...
And he learns what it is to love and be loved.
White Fang is an amazing novel of mercy and kindness and the changes those two things can wrought in a pained heart.