What does Tom want in The Adventures Of Tom Sawyer by Mark Twain?

Tom wants excitement and adventure.  In Tom's opinion, life should never be boring.  He doesn’t want adults to tell him what to do.  He doesn’t want to spend his days doing chores or sitting in church or school.  Tom prefers to use his imagination to make ordinary life more interesting. 

A good example of Tom finding something of interest in anything is the incident in church.  Tom got distracted watching a bug and a dog. ...

Tom wants excitement and adventure.  In Tom's opinion, life should never be boring.  He doesn’t want adults to tell him what to do.  He doesn’t want to spend his days doing chores or sitting in church or school.  Tom prefers to use his imagination to make ordinary life more interesting. 

A good example of Tom finding something of interest in anything is the incident in church.  Tom got distracted watching a bug and a dog.  Tom found church boring.  He got so interested in the little drama of the dog and the bug that church that day was bearable! 

Tom also had a big imagination.  He decided that he was going to have a pirate band.  His knowledge of pirate bands was based on his big ideas and some things he read in books.  He took ordinary events and pretended that they were pirate-related adventures.  

"What does pirates have to do?"

Tom said:

"Oh, they have just a bully time—take ships and burn them, and get the money and bury it in awful places in their island where there's ghosts and things to watch it, and kill everybody in the ships—make 'em walk a plank." (Ch. 13) 

Tom also is a sensitive boy.  He falls in love with Becky, and pines for her.  He thinks about her all of the time. 

Tom found himself writing "BECKY" in the sand with his big toe; he scratched it out, and was angry with himself for his weakness. But he wrote it again, nevertheless; he could not help it. He erased it once more and then took himself out of temptation by driving the other boys together and joining them. (Ch. 16)

He even asks her to marry him, telling her he is going to join the circus and be a clown.  He thinks this is an excellent plan for the future because being a clown is a very lucrative profession.  That will become less important after Tom finds the treasure in the cave.