Diabelli Project 019 - Fugue in B-flat major

The Diabelli Project is about offering my weekly flash-composition sketches freely to all. Like Antonio Diabelli's theme these sketches aren't great music. But perhaps (as in Diabelli's case) there's a Beethoven out there who can do great things with them.

Cranking these sketches out week after week, I've noticed I tend to fall into patterns. Last week's sketch was a fugue in lydian mode. This week's is a fugue in.... B-flat major. Eventually. Actually, it starts off on E-flat, which would make this E-flat lydian if I had continued outlining the triad. But I didn't, and so it eventually returns to B-flat as its tonal center.

Is that; a permanent return, or will the counterpoint wander in to another mode? C dorian, perhaps? Or F mixolydian? The choice is yours! If you use part of this sketch, let me know! I'm curious to hear how this one ends myself.