The way monolingual people often write bilingual characters, especially in scifi and fantasy, is so intensely annoying to me. For example, in the game Avowed, there's a dwarf character who says a few words in the language they use in the dwarf city he used to live in like every other sentence. But he hasn't been there for many years, he doesn't seem to have had regular contact with anyone who speaks that language during that time, and the city itself is very isolated. It doesn't make any sense.