In Roxy's old home, she often experimented with the science of ectobiology, which involves cloning with genetic samples collected through time travel. Errors in this process resulted in her owning several mutated cats. Dirk(DJ) was from this same future, and was a close friend of Roxy.

While I have you here, I'd like to clarify something: does an Echo returned by a canon recurrence have to be directly related to the recurrence, or not? I've been a tad unclear on this since I apped Roxy.