Redditors who only speak one language, what have you always wondered about bilingual/multilingual people?

Awesome question, I have a few if that’s okay!

What language do you think in?

Which language was easiest (and hardest) to learn?

Are languages a “use it or lose it” thing, where if you don’t speak/write something for a while you start to forget, or is it pretty engrained once you’re fluent?