A model family is the Grangerfords, who are feuding with the Shepherdsons.
Huck is very impressed with the Grangerford family when he comes across them.
It was a mighty nice family, and a mighty nice house, too. I hadn't seen no house out in the country before that was so nice and had so much style. (ch 17)
They may have a nice house, and a nice group of people, but they are obsessed with death. The Grangerfords will shoot the Jeffersons on sight, for no reason. The feud has gone on so long that all they think about is death. Even the paintings on the wall are about death, and Emmeline Grangerford kept an entire scrapbook of obituaries and wrote poems for the dead—until she died.
Poor Emmeline made poetry about all the dead people when she was alive, and it didn't seem right that there warn't nobody to make some about her now she was gone …. (ch 12)
Huck tries to understand the obsession with death, and the shooting at one another. The family that seems so perfect also seems so strange. He asks Buck why they shoot.
“Did you want to kill him, Buck?”
“Well, I bet I did.”
“What did he do to you?”
“Him? He never done nothing to me.”
“Well, then, what did you want to kill him for?”
“Why, nothing—only it's on account of the feud.” (ch 18)
Of course, it’s total nonsense. Yet Huck tends to take people at their word. He realizes these guys are crazy. Yet they are also basically really nice people. It is a contradiction. Huck finally goes his way, and staying with them is dangerous.
It tears Huck up inside to see Buck’s body. He considered Buck a friend. He also realizes the similarities between the two of them. The similar names are not a coincidence. Buck is a reflection of what Huck might have been, and he keeps on going.
The dueling good families are another example of why Huck does not fit into society. He simply cannot understand people's motivations. Good people, shooting at each other for no reason? This is not the civilized Huck wants to be.