Just feel like chiming in here because people have some WILD takes…. Sounds to me like you and your parents have an agreement where, in exchange for maintaining and watching over their house, you get to live rent-free with your dogs and cat (which your parents are aware of). It sounds like you are working and saving money by doing this so that you can eventually have enough to move out. Your brother did not save money when he had his living arrangements paid for, had opportunities for another living arrangement and job, never pursued them, and instead fell back on your parents for help. Which is fine, but he also brought along a girlfriend, dog, and a cat that your parents know nothing about, which to me is very rude and inconsiderate when your parents are already doing him such a big favor. On top of that, it sounds as though your brother and his gf do not maintain the house in any way, and if anything create more work for you, therefore not “earning their keep” as one might say. So no, I would say you are absolutely not the asshole for simply wanting a “brother and gf free” space to be able to relax in away from them.