Final answer:
Tom and Huck swear in their blood oath to keep the secret about witnessing Injun Joe's murder of Dr. Robinson, underlining their commitment to silence and mutual loyalty.
Step-by-step explanation:
In Mark Twain's The Adventures of Tom Sawyer, Tom and Huck take a blood oath where they swear to keep the secret about witnessing Injun Joe's murder of Dr. Robinson in the graveyard. They vow to never tell anyone about what they saw, understanding the potential danger they could face from Injun Joe if he found out they were witnesses. The ritual they perform binds them in a serious pact of silence and secrecy, demonstrating the gravity they attribute to the situation and their deep sense of loyalty towards each other.