Tom Buchanan is Daisy’s husband, an extremely wealthy man, a brute, and an athlete. He’s selfish and does what he needs to get what he wants. Most of all, he seeks control of his life and control of others. When Tom figures out that Daisy loves Gatsby, he forces a confrontation. He is then able to use Daisy’s momentary hesitation to regain control of his wife. Master of the situation once more, Tom dismisses Gatsby – and his wife – giving him permission to drive his wife home. "He won’t annoy you," he tells her. "I think he realizes that his presumptuous little flirtation is over." With that note of condescension, it is clear to all that Tom has the upper hand. Although Gatsby maintains hope beyond this scene, we all know it’s over.
But the quality of Tom that’s most likely to stick with you is the fact that he’s abusive. While we never see him get violent with his wife, there are hints of his unbridled physicality when Daisy reveals a bruise on her finger that, although accidental, was caused by Tom (or the "brute," as she calls him). Although he might not be physically abusive to his wife, Tom certainly causes her some emotional damage. There is, of course, his series of affairs, but he hurts Daisy in other ways, too. When Daisy tells us about her daughter being born, she casually adds that "Tom was God knows where." He is neither attentive nor sensitive towards his wife – especially in contrast to Gatsby. But, of course, Tom’s violent streak really comes across when we see him break Myrtle’s nose with the "short, deft movement" of his open hand. The curt language Fitzgerald uses here makes it clear that such violence means little to Tom.