Howling:Cybermen merging universes

In the Doctor Who/Star Trek: The Next Generation comic crossover Assimilation2, it is heavily inferred that the Cybermen have somehow merged the individual realities of the Doctor and Star Trek together, so even their past histories are affected (Judging from the Fourth Doctor's interaction with the crew of the original USS Enterprise in the 23rd century). But are there any theories as to how exactly they are able to accomplish this? Reality-merging seems like something far beyond their capabilities. Could they have had help? If so, from whom? And also, at the end of the story, the Doctor tells the Enterprise-D crew that once he and his companions depart in the TARDIS, and with the Cybermen wiped out, the realities should separate again and their histories return to normal with no trace of the Cybermen's activities remaining (The Enterprise crew, however, will apparently still remember everything that's happened). What makes the Doctor think this is what will happen? As far as I can tell, whatever method the Cybermen used to merge the realities has not been reversed with their destruction. Any ideas? 82.20.113.152talk to me 11:15, February 16, 2013 (UTC)