AITA for stepping into an argument between my sister and my 12-year-old brother?
I (31F) invited my sister (30F), my boyfriend(31M), my roommate(31M), and my younger brother (12M) to go see a movie this weekend.
At first, I planned on bringing my brother because he's seen other scary movies before and handled them fine. My sister was concerned because the movie is rated R, which I understood. So I showed my brother the trailer and asked if he was actually interested.
He said no.
I told my sister he wasn't interested anymore and that it would just be the adults going. I also told her that if she wanted to talk to him herself, she could call him since he has an iPad.
She did call him, but instead of accepting his answer, she started asking questions like "How often do we see each other?" and telling him he spends too much time on his PlayStation. Her tone became increasingly hostile and she raised her voice.
My brother started giggling because he thought the situation was ridiculous. My sister got even more upset and said he was being disrespectful.
At that point I stepped in because I didn't like how she was speaking to him. I told her that if she wanted more quality time with him, she could spend time with him separately and didn't need to make the movie a big issue.
She got angry and said the conversation was between her and my brother and that I shouldn't interfere. The argument escalated and she eventually hung up.
Afterward, she texted me calling me selfish, a narcissist, and a terrible person.
Later, my brother called her back on his own. He tried to explain that he felt her reaction was unfair and even told her, "If I say no, then you should accept my answer and move on."
According to him, she actually responded that she didn't agree with that.
Eventually my brother changed his mind and agreed to come to the movie, and my sister finally calmed down.
From my perspective, the whole issue started because my brother said he didn't want to go to a movie and my sister refused to accept that answer. My sister's perspective is that my brother was disrespectful, I undermined her authority, and I should have stayed out of their conversation.
AITA for stepping in?