What aerodynamic implications would a fictional two-pronged fuselage have?
I don't see any benefit (besides optics, but this is debatable). Compared to a single fuselage, these disadvantages exist:


More wetted surface for the same volume, so more friction drag.
Twin fuselages will obstruct the pilot's view more than one.
The two-pronged fuselage has a higher roll inertia, so it reduces agility.
Any instrumentation will be blocked at the side of the other fuselage, so you need more complex sensors and a sensor fusion algorithm.
The wake from the fuselage will affect the wing more than that of a single fuselage. One consequence will be lower maximum lift of the wing. This is compensated by forebody lift, but this lift is created in a very inefficient way.


Also, the fin in the picture is too small to provide sufficient directional stability without artificial enhancement.