This is what they look like when they merge, its pretty darn cool
I love to contemplate galactic-scale synchrotrons that accelerate supermassive charged black holes to collide at relativistic speeds. The thought never really goes anywhere, but I'm sure it'd be a spectacle to behold.
It would be just about the only way we could get the data required to resolve the contradictions between the Standard Model and general relativity. The unification energy is simply stupendous.