Why the love story between Katherine and Sam important

I think that the love story represents the spirit of this book. Holes is a book about outsiders being heroes. The boys in "remedial camp" are looked down on by society, yet they posses a rebellious sense of honor. Similarly the relationship between Katherine and Sam is seen as forbidden and wrong. There love, however, is real. They rebel against the conformity of society. Kate Barlow becomes an outlaw: her rage represents her reaction to the racism that she and Sam had to endure.