I thought long and hard about the question of mixing universes, and
allowed it only in this one case, because the events that propelled Trent (the
character from Demon) into the past (our present) don't take place for another
thousand years or so. Thus it doesn't do my arc any harm at all. One could
say that the events in "Demon" will happen at some point in the future of the
B5 universe...unless some events change them. On this one occasion,
therefore, I decided to allow it. But that's the ONLY one.