Huckleberry Finn, Racism?

I have to write a 5 page essay on what affected mark twain in writing the book and what the book may have affected. All of this has to relate to racism. I'm writing that when he got married, he became aware of the abolitionist movement and became a supporter and how he portrays huck finn as an abolitionist. Any suggestions for another idea or two because i doubt i will be able to write 5 pages about tha