In this story, Bud Lawrence is a "leading citizen" of Westfield and the wealthy owner of two restaurants. Overall, he's opportunistic, clever, and manipulative. Depending on your point of view, you could also say that Bud is generous, or at least, reasonable.
Opportunistic people are those who take advantage of whatever situation they're in so they can use it for their own (often selfish) purposes. That describes Bud exactly. When the whole "frindle" trend is just starting to gain traction, Bud asks his lawyer to file a preliminary trademark claim on that made-up word. That allows him to sell things, like pens and t-shirts, with the word "frindle" on them. Although what he did was perfectly legal, it wasn't very honorable of him. "Frindle" was Nick's invention, not Bud's, so it's opportunistic for Bud to just leap onto the idea for his own profits.
However, you have to admit that what Bud did was clever. He made thousands of dollars from that project because he understood what people were currently interested in and what they wanted to buy.
Bud is definitely manipulative, though. He would rather keep all of his profits for himself, rather than sharing them with Nick, the real inventor of "frindle," but Bud's lawyer tells him that's a bad idea. Everybody knows who made up the word! The only reason Bud decides to bring Nick in on the profits is because his lawyer tells him he's got to so as to avoid getting in trouble. Notice how manipulative (controlling and sneaky) Bud is when he talks to Tom, Nick's dad. Bud is practically grinning with glee when he realizes that Tom is tired of the whole "frindle" affair and is ready to put it behind their family. It's easy for Bud to get Tom to sign the papers giving Nick only a portion of the profits. Tom doesn't even try to negotiate any of the terms.
So, Nick will get 30% of Bud's profits from capitalizing on the "frindle" trend. It's already over two thousand dollars! Does that make Bud generous? Sure, from one perspective. From another, though, the 30% is just reasonable. Without Nick, Bud wouldn't be making any of that money at all. Doesn't he deserve more than a third of that income? It depends on how you interpret the whole situation. And it's not like Nick did nothing to earn that money. He had to talk to reporters and other members of the media, and he had to endure the changes in his daily life that came with being famous.