What's the problem in Freak the Mighty?

There are two main problems in Freak the Mighty: one has to do with the villain of the novel and the other has to do with Kevin’s birth defect.  

The first main problem has to do with the villain of the book: Kenny “Killer” Kane (Max’s father). This character darkens the entire book; however, we first begin to realize what a scary character Kane is through Max’s reaction to the principal’s news that Max’s dad is about to get out of jail on parole. As a result of this news, Max falls into hysterics, which eventually leads to a loss of memory about the whole incident. Kenny “Killer” Kane remains an ominous and unseen figure until the end of the book where we see exactly what an evil character Kenny “Killer” Kane truly is. Kane kidnaps Max while we learn that Kane truly did kill Max’s mother.

The other main problem in the book is that Kevin has a severe birth defect. As a result, Kevin’s legs are severely deformed. Kevin cannot get around without braces and crutches. The positive effect of Kevin’s condition is that Max and Kevin are able to create the unified character of “Freak the Mighty.” When Kevin gets around on Max’s shoulders, the two become a force to be reckoned with. More serious than the issue with Kevin’s legs, though, is the fact that Kevin’s heart is “too big for his body.” This causes Kevin’s eventual death.