He confused me about Pat Tallman and Andrea too. I didn't know that originally, there was only one telepath in the storyline.
Yes, there was supposed to be one telepath - Lyta. She was introduced in the pilot and scanned Kosh. Either this alone or a subsequent trip to the Vorlon homeworld would have started her powers increasing, and she would have ended up about where she did at the end of S5. JMS actually wrote the part of Lyta with Pat Tallman in mind. He had seen the remake of
Night of the Living Dead and decided she had the eyes of a telepath.
Unfortunately the studio failed to make a deal with Pat for the series. (While JMS, as the producer, had the most influence over casting, the studio ultimately paid the bills. The actors were under contract to
Warner Bros. and therefore the studio had to sign off on JMS's choices and make the actual deals. One reason there were so many other changes between the pilot and the series was that after reviewing the completed film both JMS and Warner Bros. weren't thrilled with how everything came out. That's one of the reasons you
make a pilot, to get the thing on its feet and see what works and what doesn't.)
So JMS created Lyta and Andrea Thompson was cast. Lyta was mysteriously reassigned to Earth (as was Dr. Ben Kyle) and Laurel Takishima sent out to the Rim on a secret mission. This meant that everyone who either saw Kosh or was in MedLab when the encounter suit was opened was off the station within a matter of weeks and added to the intrigue.
Jason Ironheart was created to give Talia increased power through another path. In the first instance Lyta scanned Kosh, and thus formed a bond with the Vorlon. This would lead them to trust her and eventually enhance her for their own purposes. In Talia's case she was enhanced first - and this got the Volrons interested in her, when they normally avoided telepaths. The VCR recording was no doubt part of the process of connecting the Vorlons to Talia. The Sleeper personality, and the way it was utlimately reversed, might also have played into this thread. (The recording could have been the basis for the restoration of Talia 1.0, and the Vorlons might have done a little further tinkering while they were inside her head.)
When Andrea decided to leave, JMS pulled the trigger on the Sleeper personality and made it permanent. Pat came back for the guest shot to remind everybody who Lyta was, and the character was packed off to the Vorlon homeworld, ready for her return the following season. (Luckily WB was able to make the deal this time around. It was too late for Lyta to return in S3 anyway, since "Divided Loyalties" was shot as episode 220.)
Lyta then pretty much picked up her own original thread where she left off and continued on from there. The VCR recording, Talia's mentor at Psi Corps and other threads were allowed to quietly fade away as they were no longer needed.
Regards,
Joe