Final answer:
Scout fights her cousin Francis because of his insulting remarks about her father, highlighting key themes in 'To Kill a Mockingbird' about racial injustice and moral development.
Step-by-step explanation:
Scout fights her cousin Francis in To Kill a Mockingbird because of his derogatory comments about Atticus, Scout's father. Francis calls Atticus names and criticizes his defense of a black man, which provokes Scout to physical altercation. The novel explores themes of racial injustice and moral growth, and Scout's reaction to her cousin's insults reflects her own developing sense of right and wrong, influenced by her father's values and the community's attitudes towards race.