Abstract: In order to discuss black holes in a doubly-holographic setting in three bulk dimensions one usually considers a bottom-up model in which an end-of-the-world (ETW) brane is introduced, whose action is that of JT gravity. This raises the question how JT gravity appears as the brane action. In this talk I will explain that quite generally, deformations of 2d ETW branes are controlled by a particular dilaton gravity coupled to a large-c, effective CFT. This dilaton gravity is related to Liouville Theory and reduces to AdS-, dS-, and flat-JT gravity in various limits of the branes' tension and at large central charge. Using the bulk picture of double holography, this perspective allows to derive the correct area functional for extremal surfaces in the presence of JT gravity on the brane. I will moreover argue that adding JT to the ETW brane is equivalent to infinitesimal deformations of the BCFT boundary.