I had never considered the possibility that JR may have started out resenting having to do the dirty work necessary to keep Ewing Oil on top while Bobby was out wining and dining clients until just recently, while reading a post by @Lastkidpicked. The two of us were discussing JR's role as a young man in Ewing Oil compared to Bobby's role as a young man in the company and how the differences in their roles may have created resentment on JR's part. Starting with that in mind, I took the idea and expanded it into a possible explanation of how the two brothers' involvements in Ewing Oil led to them both being dramatically changed by the experience, each in his own distinct way. JR's job was seen by most people as the more important, prestigious job. That's why in the first episode of the series, Pam tells Bobby he should be doing what JR is doing. Bobby should have laughed at the idea, but he was still quite young and I doubt he fully understood what the job entailed. I'm sure he didn't realize how doing JR's job would affect him. I wonder how much doing that job changed JR. We won't ever know because the show didn't begin until he was already involved in running the company so we can only speculate, but it's a fascinating subject to think about because it applies to us all to some degree. How do the careers we choose change us? Do they change us for the better or the worse? Suppose as was suggested, that JR initially resented "slaving away at the office" and "doing the dirty work" as @Lastkidpicked put it. In that scenario, JR is doing the most undesirable tasks required to keep Ewing Oil on top, or even competitive, while Bobby is giving people season tickets to see the Dallas Cowboys and taking them out to fancy restaurants and glamorous nightclubs. Bobby's job requires being charming and making sure everyone is having a good time. JR's job is having to be the person who makes the call to lay off people approaching retirement age so they either don't collect their pensions or collect pensions that are a fraction of what they would have been a few years later. Bobby's job is to make people happy and help get them things they've been having trouble getting on their own. JR's job involves crushing people's hopes and trying to ensure they won't get what they want. Bobby's job makes people talk about him and say what a great guy he is. JR's job makes people talk about him too, but in terms of: "How are we going to stop him from driving us out of business"? Right away, they've been placed on career paths that put them in diametrically opposed environments. Bobby hears people saying what a great guy he is every day. JR hears people talk about what a bad guy he is every day. Bobby grows to be genuinely liked by the people around him because he's always in situations with them where they're either having a great time, or if not, Bobby figures out a way to make their lives at least a little bit better. It's easy for Bobby to be generous because he's being given practically unlimited funds with which to do it. JR's job is to give pay his workers as little as he thinks they'll accept and to buy people's land for as much less than it's worth as he can get away with. If someone is in a bind, it's Bobby's job to get them out of it, while it's JR's job to exploit it! While Bobby is hearing everyone telling him what a great guy he is and starting to believe it, JR is hearing people say the opposite of him and it starts to affect his perception of himself as well. JR takes a look around to see if there is some better way to go about things, and finds out all his competitors do the same thing. Whoever screws people the hardest wins. Familiarity breeds contempt. No matter what it is. The more familiar you become with it, the more contemptuous you become of it. The more negative opinions of JR that get back to Bobby about how JR is running the company, the more contemptuous Bobby becomes of JR. Pam tells Bobby he should be doing what JR does and he starts thinking, there has to be a better way to do this. People hate JR's guts! He's giving our company a bad name while every single night I'm out at the restaurants, the bars, the nightclubs, trying to fix the damage he's been doing to our company's reputation. If I were running the company, we wouldn't be having all these problems! Bobby finally tells Jock he's done being “The B Man” for Ewing Oil because he wants to learn to run the company. Jock says that's fine and tells JR to start teaching Bobby the business of running the company. Almost right away, Bobby asks to see The Red Files. Bobby is now privy to the most unsavory information about the whole company. He's appalled. For years as the company's road man, he's heard rumors about some of this, but dismissed it as mere assumption and conjecture. Now he's looking right at the actual information. He hates what he sees. He's disgusted at the types of deals and behavior his father and brother have become involved with and has come to the realization that he not only should, but must run the company. Bobby is convinced he's the only family member with the aptitude and the desire to do what needs to be done. It was bad enough when he was hearing about his family dealing from the bottom of the deck, but now he's got all this information in front of him. He can't dismiss it as just opinion any longer. He now has the knowledge to back up his growing belief that he's the man who should be running Ewing Oil. He knows he could do the job better. There's just one problem with all of this: Real knowledge is not information. It is a matter of information and experience together that make real knowledge. When JR gets shot, Bobby finally gets full control of running the company. He's going to show them how it's done. It starts off alright, then a problem arises, then another and another. He eventually learns it's impossible to run the company the way he envisioned. After a few months he hands back control of the company to JR who says to Bobby he's lost them millions of dollars. Bobby tells JR that he's sure JR will find a way to get it back and adds: "You're much better at that sort of thing than I ever want to be." Bobby had the information before but now he has true knowledge of what it takes to successfully run the company. JR knows what it takes to run the company and maybe he resented at it first, but he responded differently than Bobby did. He looked around at how all his competitors operated and his resent turned into contempt. The more familiar he became with the business, the more contemptuous of his competitors he became. He saw them all bending the rules whenever they saw fit while pretending to be ethical businessmen and fine upstanding pillars of the community and he just saw a bunch of phonies. JR saw there was no honor in the business and figured: Why pretend to be something you're not? Every day they claim to be one thing and act like something entirely different. I'm not gonna pretend to be ethical. You wanna call me "wrong" and "cruel"? I'll embrace it! JR doesn't want to be a nice guy and no longer pretends to be one. He's found something he's better at than anybody else and he's learned to love it. Bobby kept trying to find a way to run the company in an ethical way and kept running into situations where that wasn't possible. No matter how hard he tried to be fair and honest, he inevitably ended up with somebody pissed off at him. There was no way to please everybody and what was the point in trying? People like Jordan Lee were saying "Bobby's becoming just as bad as JR. Given the chance, he might turn out worse." The more familiar Bobby became with the business, the more contemptuous he became of how impossible it was to run the company in a way where being good would be rewarded. Bobby didn't learn to relish being devious. Bobby couldn't be proud of having a reputation of being the baddest of the bad. He couldn't be satisfied finishing last either, so his contempt of the whole industry grew to the point where he was absolutely done with it. JR's contempt of the rest of the people in the oil business grew to where he not only didn't mind treating them badly; he learned to love it. Bobby's contempt of the oil business grew to where he decided to leave the entire industry. He sold Ewing Oil with one stipulation: that his family's name no longer be affixed to the name of the company.