Tom and Becky:
Tom and Becky are an "engaged" couple who often fight about being loyal to each other. Tom, who was initially engaged to Amy Lawrence, saw Becky and gave up on Amy. Tom loves Becky a lot, but gets annoyed and tries to make Becky jealous, but he eventually feels bad and pays for it. In one instance, after Tom comes back from the island, Tom ignores Becky and begins talking with Amy Lawrence and Becky, trying to get revenge and begins to read a book with Alfred Temple. Later when Tom tries to apologize, Becky refuses the apology, and resolves to let Tom get whipped. Tom later finds Becky reading the teacher's medical book, and a frightened Becky closes the book as fast as she can, accidentally ripping the book, but Becky thinks that Tom will tell on her. Instead, Tom accepts blame for ripping it and their relationship becomes better from there. Later when Tom and Becky are lost in the cave, Tom gives Becky part of his cake, consoles, and helps Becky get out of the cave. Towards the end of the book, Becky describes all the good things that Tom had ever done to her father, who was mighty impressed with the treasure he found.
Tom and Huck:
Tom and Huck are great companions. Tom loves being with Huckleberry Finn, because all the parents forbid being with him and he is very friendly. They experience many adventures together, such as being a pirate and hunting for treasure. As a pirate, Huck teaches Tom and Joe how to smoke a pipe. Huck rarely leaves Tom's side, as the two are like brothers. Huck and Tom are both very mischievous, but Huck, due to his father being a drunkard feels uncomfortable around society. Fortunately, however, Tom is usually able to convince Huck otherwise. Later on in the book, Tom and Huck find treasure and split it, revealing how good friends they were.
Tom and Joe:
Tom and Joe Harper are great friends and somehow experience very similar things. For instance, the same day Tom wants to become a pirate because he was yelled at, Joe is yelled at. Consequently, both of them go to become a "pirate." On the island, they both want to learn how to smoke a pipe, and they both fell sick. Joe and Tom are sworn friends. He is not mentioned that much towards the end of the book except when Becky's mom and Aunt Polly are interrogating where their children/nephews were.
Tom and Sid:
Tom and Sid are half-brothers who try to get each other in trouble. In the beginning, Sid tells Aunt Polly that Tom resewed his collar the wrong color, which leads to Tom getting in trouble. Afterward, Tom gets Sid back by hurling clumps of dirt, shortly after he pleases his Aunt Polly. Later, when Sid reaches to get sugar, he drops the sugar bowl, and Aunt Polly who didn't witness thinks Tom did it and immediately hits him, without asking who had done it. Tom then becomes "depressed" and lays down, pretending dead near Becky's house. There he gets water dumped on him.
Tom and Injun Joe:
Tom and Injun Joe are in a way enemies, although Injun Joe has made no actual indication that he wants to kill Tom. Tom reveals that it was Injun Joe who had killed Dr. Robinson, and this leads Tom to believe that now, Injun Joe would try to kill him. Tom and Huck keep a watch on Injun Joe and his acquaintance and therefore tries get hold of the treasure, although knowing the risk if they are caught. Injun Joe who had gone in the cave to bury the treasure was trapped inside when Judge Thatcher gets some men to seal off the cave, not knowing someone was still in their. Tom then reveals upon hearing this that Injun Joe was in the cave, and when they look, he apparently had died due to starvation.