contrary to popular belief, someone who is fluent in their second language (L2) is unlikely to slip into their first language (L1) in these circumstances:
if someone just said something to them in L2 (this a big unconscious cue, and you’d be really unlikely to respond in L1 right after that)
when swearing in the middle of a sentence (e.g. “oh merde, i forgot my keys!”)
during sex
when speaking to someone they normally speak to in L2
it is slightly more common in these circumstances:
swearing, as long it’s not part of a sentence (e.g. they might just mutter “merde” if they forgot their keys)
if they’re surprised (especially if falling/tripping or experiencing sudden pain!)
when speaking to someone they normally speak to in L1
in their sleep or talking to themselves
when very disoriented, such as when concussed or on certain drugs
that being said, it is very common for people to intentionally use their first language in front of people who don’t speak it for a variety of reasons (they might use a short expression they only know in L1, call their partner pet names, dirty talk during sex because their partner finds it attractive) – but this is on purpose!
also this doesn’t account for people who grew up in an environment where people often mix multiple languages in their speech (e.g. spanglish or franglais) – in that case, they may accidentally drop an L1 swear into an L2 sentence, though they’ll still generally stick to L2 when speaking to people who only speak that language
@writingwithcolor if you havent seen this already this looks really helpful for writing bilingual peopel
