Use the Fascia tool to add fascia to edges of roofs, soffits, model lines, and other fascia.
As you click edges, Revit treats this as one continuous fascia. If the fascia segments meet at corners, they miter.
This different fascia does not miter with other existing fascias, even if they meet at the corners.
Fascia profiles miter correctly only around a square cut roof. The roof in this image was created by running a fascia along the edge of a roof with a Two-Cut Square rafter cut.