If your Ragavan, Nimble Pilferer's damage trigger exiles a Brazen Borrower, and you choose to cast the Petty Theft portion of the card, what happens to the Borrower? Does it go on an adventure, and if so, can anyone cast it from the adventure zone?
716.3. As a player casts an adventurer card, the player chooses whether they cast the card normally or
as an Adventure.
716.3d Instead of putting a spell that was cast as an Adventure into its owner’s graveyard as it
resolves, its controller exiles it. For as long as that card remains exiled, that player may cast it. It
can’t be cast as an Adventure this way, although other effects that allow a player to cast it may
allow a player to cast it as an Adventure.
So you as the caster of the adventure also get to cast the exiled adventurer. And only you.