How does Twain establish Huck Finn as a mischievous rascal?

The Widow Douglas want to "civilize" Huck, and Huck wants nothing to do with it so he runs away. Tom on the other hand wants Huck to come back, so he does a bit of jostling words;

"But Tom Sawyer he hunted me up and said he was going to start a band of robbers, and I might join if I would go back to the widow and be respectable."

It's just a bit mischievous to be a "respectable" robber, but Tom pulls it off!