Well this is a really debatable question. If by ethical, one means whatever should take place in a workplace setting, then I guess you could say that Brian was acting unethical. He wasn't working to begin with, but like, that seems like something that's his choice. There wasn't anyone demanding it. Regina made it clear his quarterly was important, which indicates it might me due soon, and he was kinda playing poker. But that was his choice, which he's gonna have to account for when his boss doesn't have the quarterly. It also seemed that he was using company funds for personal things, which he will still have to account for, otherwise that's a flaw on the company's part, which they may want to work on. And accepting gifts from clients, and taking them to lunch, personally I think that's a choice that the two people can make on their own, as they are humans and not robots, and it also really depends on your job. Sometimes this is something that might help with your job, taking a client to lunch and going over details.
As far as it being any of Regina's business, I mean if she's curious she's curious. Only if the boss asks her, and she doesn't tell him something and he later finds out that she knew, that might not work out in her favor. But as far as it being her business, if that's you're colleague and you share a space, and you work for the same company, then you would want to help your company (depending) and you'd want your colleague to stay out of trouble, unless you don't like them cause they're a douche. I think ethical behavior is really subjective, and depends on a lot of factors.
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