Miles kind of plays second fiddle to Jesse in Tuck Everlasting, but he definitely has his moments. And we're here to scope them out.
In the years between hitting the spring and realizing he was immortal, Miles fell in love, got married, and had a family. Sounds all well and good, right? But when it became clear that he wasn't aging, he lost it all:
"I was more'n forty by then," said Miles sadly. "I was married. I had two children. But, from the look of me, I was still twenty-two. My wife, she finally made up her mind I'd sold my soul to the Devil. She left me. She went away and she took the children with her." (7.16)
Out of all the Tucks, Miles might just have it the worst. But why didn't he just ask his wife and children to drink from the spring, too? (That's pretty much what Jesse does to Winnie, right?) Maybe he's more like his dad than we might think; maybe he thinks immortality is a curse, and he just doesn't want to share the burden with his family.
Miles's shining moment comes when he takes Winnie out on a fishing trip.
Winnie thought about this peril to the frogs, and sighed. "It'd be nice," she said, "if nothing ever had to die."
"Well, now, I don't know," said Miles. "If you think on it, you come to see there'd be so many creatures, including people, we'd all be squeezed in right up next to each other before long." (17.18-19)
This isn't the deepest thought anyone's ever had, but he's really trying to get Winnie to think about all sides of immortality. And he respects her point of view, too. When Winnie asks him to put the fish they catch back in the water, he doesn't hesitate. So he helps her understand the necessary nature of death, but he protects her from having to face it that very day.