I'm going to post what i know about the original outline/story for B5. I will also put up some campaign ideas. If anyone else knows any of JMS' unused plot points for B5, post 'em and, if possible, give campaign ideas
Cmdr SinclairOriginally Sinclair was to remain throughout the series and be involved in the shadow war and the Civil war. He would eventually take his place as Valen at the end of the series. JMS realised that he had thus boxed Sinclair in to a narrative corner with little room for character development. Ergo Sheridan was introduced.
Catherine Sakai - Sinclair's on/off girlfriend.
Originally, she was planned to go on an expidition to Z'ha'dum during Season 2. She would return is Season 3 luring Sinclair to Z'ha'dum. When Michael O'Hare left after s1, the relevant plot points were carried over to Anna Sheridan
Laurel Takashima - original 1st officer
Called Laurel Chang in the original treatment.
Originally, she was to have been involved in assassination attempt on ambassador Kosk as the insider. She was to be the one who housed the Control personality and under its control the one who shot Garibaldi. When revealed as control, she would have been relieved and replaced by the Russian 2nd Officer, Susan Ivanova.
Also Takashima would have been in an intimate relation ship with Ivanova.
Personallity and plot elements for this character were transfered to Talia Winters and Jack (Garibaldi's Second)
*It also seems like this original idea for Takashima was used for the Lt Boomer that shot Cmdr Adama in BSG (RMD)...possibly coincidence
DelennDelenn was to originally be a male character. When he underwent the transformation, he would have become female...
Taila WintersI presume that she was introduced when Patricia Tallman didnt originally sign on for the series. I futher presume that she would have gone on to fufill Lyta's role in the series had Andrea Tompson stayed.
Also does anyone remember the Data chrystal that "Abbut" recorded and gave to Kosk in "Deathwalker"?Well if Mrs Tompson had remained with the series, it would have been revealed that it contained a copy of Talia's personality. Kosk would destroy the Control personality and use the crystal to restore Talia
Ivanova(See Takashima)
Also had Ivanova been in season 5, She would have had the romance with Byron. It was instead transfered to Lyta
THE VORLON EMPIRE
Originally the Vorlons would not have been "Ancients" they'd be one of the 5 modern big races. They would also have been a very different race. Something like a cross between the "Terran Empire" from Star Trek's Mirror Universe and X-File's "Syndicate"
*This would make a rather interesting campaign...Metallic reskins of the vorlon ships and possibly playing a Vorlon pilot in a Vorlon Civil war
BABYLON PRIME
http://en.wikipedia.org/wiki/Babylon_4 this would also make a great basis for a campaign...and a chance to use the B4 model for something different
PS does anyone have that Poster which had the original Pre-Pilot Treatment on it?
PPS I will ask for anyone who posts the link to that "Babylon-5: The Anime" prank site to be banned