I have always loved animals. So most of what I read as a child involved animals...or mysteries. The Call of the Wild and Where the Red Fern Grows were both so touching. The bond between a person and an animal can be just as deep, sometimes deeper than the bond between people.
I remember my third grade teacher (my oldest daughter is now in the third grade) read Where the Red Fern Grows to us, one chapter a day. I looked forward to that half hour every day. So for me, that is the book that hooked me to characters.
As for The Call of the Wild: But love that was feverish and burning, that was adoration, that was madness, it had taken John Thorton to arouse. While he went wild with happiness when Thorton touched him or spoke to him, he did not seek these tokens. --excerpt from Call of the Wild.
This story is such a great lesson for anyone and everyone. Though you can love someone with fever and burning, you can never abandon who you are. Jack London's work has amazed me since that first page. So I have two favorites.