Twain creates pathos when Sally is overjoyed to see Huck and when she is upset that Tom is not back.  Another example is when Huck vows never to upset Sally again.

Jim was lonely and wanted Huck to stay.  In additon

Tom knew all along that Jim was a free man.  He was unsure of whether to reveal his information.  The information was in between the lines.  Tom could have freed Jim easily with the knowledge of the will, but Tom wanted adventure.