Why do you think Stowe chose to have Tom owned by different masters in the book?

There are different experiences that Tom has from master to master. Arthur and Emily Shelby, for example, are affectionate towards Tom while Mr. Haley is cruel and nasty to Tom. This tells us that although the idea of slavery was acceptable across mainstream white Southern culture, the way they were treated varied. I think Tom also has a profound affect over many of the people he comes in contact with. Tom is almost a Christ figure. He brings out the good in people if there still is room to find it. Ophelia, for example, learns to cast her bigotry aside in part from Tom's gentle influence.