Especially if the other person is related to me. My father never liked it when I went to see films alone. He was afraid that strange men would sit next to me and would try something in the dark. But these are reasons why you might not go to one movie alone. It's fun because I can lose myself in my thoughts and not neglect anyone.
Some movies demand a group, however.
Of course, everyone in the theater knew the script verbatim, including me. It was extremely dorky, but it was a blast. We're both quick to spot cliches and love making snarky comments about them. We can only do this together, since wiseguy remarks tend to annoy other people. What I hate, however, is when I'm watching a video with people and a sex scene is on.