expression, ichidan verb
sit together in a friendly way; have a heart-to-heart talk
Literally 'to cross knees', used figuratively for sitting close and talking intimately or amicably. Often implies a relaxed, open conversation.
久しぶりに旧友と膝を交えて話した。
I had a heart-to-heart talk with an old friend for the first time in a while.
彼らは夜遅くまで膝を交
They sat together talking intimately until late at night.