Character1: dialogue Character2: *action* Character1: ... Character1: dialogue
In the context of fanfiction, they're sometimes referred to as drabbles. But the official definition of drabbles is 100-word fiction and not usually in that format. In the context of Twitter or memes, they're used commonly as a way of recounting some funny exchange.
They're somewhat like scripts, with dialogue, actions surrounded by '*', no narration, no POV, no setting. Just a character/name followed by dialogue/action.
Is there an official term for this kind of written work? Thanks!