All their children have 'flown the coop'. [=have moved away from home]
Her books are filled with abstract ideas and 'high-flown' language.
In the morning the suspect had 'flown the coop'.
(..) You're the Mother of Dragons. Show your strength. No one's seen Drogon in weeks. For all I know, he's flown halfway across the world. The wise masters ask for the reopening of the fighting pit. Where slaves fought slaves to the death? (..)2015 TvShow: Game of Thrones Title: Kill the Boy Season: 5 Episode 5