Who Framed Sinclair?
In "The Gathering", Babylon 5's pilot, Commander Jeffrey Sinclair was framed for an assassination attempt against Vorlon Ambassador Kosh. In my opinion, the true culprit of the conspiracy to frame Sinclair has never been revealed. You may be surprised with the party I think is responsible.
Commander Sinclair was the victim of a huge conspiracy. The assassin himself was a Minbari member of the Windswords clan. This renegade warrior caste clan was interested in Sinclair. They knew that Sinclair had been captured by the Minbari Grey Council, tortured, and released with his memory erased before the surrender at the Battle of the Line. This was revealed by the Minbari's line to Sinclair, "There is a hole in your mind," referring to Sinclair's missing 24 hours.
The second participant of the conspiracy was Del Varner, and illegal technology runner. He provided a changeling net, a device the assassin could use to mimic the appearance of anyone he recorded.
The assassin was brought to Babylon 5 on a Narn transport. Del Varner was supposed to meet the transport before it arrived at Babylon 5 to give the changeling net to the assassin. The assassin would have used the net to leave the transport disguised as a Narn because suspicions would be aroused if a Minbari was seen leaving a Narn transport. When Del Varner missed his rendezvous with the Narn transport he proceeded on to Babylon 5.
When the Narn transport arrived at Babylon 5 without the changeling net the Minbari assassin had to be smuggled on board using a small spider transport that attached itself to the station's hull.
The Narn complicity was further demonstrated by Ambassador G'Kar's actions. He argued for the transport to be allowed on the station without a search, hoping that Del Varner could bring the changeling net to the ship in the docking bay. Once the assassin had left the transport, G'Kar graciously consented to the search. G'Kar was also in secret contact with the Vorlon government to secure their vote during Sinclair's hearing and blackmailed Centauri Ambassador Mollari for his vote. This ensured that his motion to remand Sinclair to Vorlon custody would pass.
Another member of the conspiracy was closer to Sinclair than he ever realized: Lieutenant Commander Laurel Takashima. She failed to notice the spider transport attaching itself to the station. She provided the assassin with her access code to enter Del Varner's quarters as indicated by the control panel beside the door. She stopped Sinclair's transport tube car to keep him away from the docking bay during the assassination attempt. She deleted the computer records of the tube car malfunction, erasing Sinclair's alibi.
All the pieces of the conspiracy were in place. The assassin was on the station and had access to Del Varner's quarters. He killed Varner and assumed his identity with the changeling net to move about the station. While Takashima held Sinclair up, the assassin posed as Sinclair to meet Ambassador Kosh in the docking bay. Kosh recognized Sinclair as the man who would become Entil'Zha Valen and granted him unprecedented access, exposing his hand, to which the assassin applied a poison skin tab. Later, the telepath Lyta Alexander scanned Kosh and identified Sinclair as the assassin.
G'Kar seems to be the mastermind behind the conspiracy. He even states his motive in the show: to start a war between the Humans and the Vorlons while encouraging the Minbari to ally with the Narn. The Windswords clan also have a motive. They want to remove Sinclair, whom the Grey Council perceives as a link between the Humans and Minbari. The Grey Council thinks he is Valen reincarnated. The Windswords are apparently upset by this notion and would go to great lengths to discredit Sinclair.
There is, however, one small occurrence that casts doubt on this explanation and leads me to believe that there is one more player in this conspiracy.
Why did the assassin offer to cover Londo's bets while disguised as Del Varner?
Londo Mollari was gambling in the casino. He ran out of money, but a man named Del Varner offered to cover his bets. This kept Londo in the casino longer and made him miss his appointment to meet the other delegates to receive Ambassador Kosh. On the surface it seemed to be a feeble attempt to implicate Londo since he wasn't where he was supposed to be at the time of the assassination attempt. The move was feeble because Londo had an ironclad alibi. Plenty of witnesses could account for his presence in the casino. How could anyone not notice the boisterous Centauri? The casino probably even had video cameras. Security Chief Michael Garibaldi quickly eliminated Londo as a suspect.
What did the assassin accomplish by offering to cover Londo's bets? He gave Del Varner's name to Londo. He ran off without giving Londo the money and was absent from the casino at the time of the assassination attempt. He also made Varner appear in public after the time of his death.
What did the assassin accomplish? He gave Garibaldi his only clue that allowed the crew to unravel the mystery and save Sinclair.
Del Varner was the only name Garibaldi had. It was a long shot, but when he investigated he found Varner dead in his quarters and computer records indicating that Varner had brought a changeling net to the station. It was easy to deduce that the assassin had impersonated Sinclair during the attack on Kosh. An internal sensor scan identified the high energy produced by the changeling net, and Sinclair and Garibaldi were able to confront the assassin.
Giving Del Varner's name to Londo was a stupid and pointless move... unless the assassin wanted to be caught.
Why would the assassin want to be caught? Were the Windswords double-crossing G'Kar? What would either G'Kar or the Windswords gain if Sinclair was absolved of the crime? Nothing. That is why I believe there is a fifth party to the conspiracy, a party that had something to gain if Sinclair was put on trial but eventually proven innocent.
I believe the Vorlons are behind the conspiracy.
What was their motive? What did the Vorlons gain?
At this point in time, the Vorlons were an unknown power except to the Minbari. Their power was based solely on the other governments' fear of the unknown. This fear was only supported by myth and hearsay. It is entirely possible that some of the younger races wondered if the Vorlons were just a paper tiger.
Sinclair's trial and G'Kar's surprising motion to send Sinclair to the Vorlon homeworld allowed the Vorlons to send an impressive fleet to Babylon 5. This fleet was many times larger than necessary to destroy Babylon 5 or defend itself from any nearby Earth Force ships. The fleet was only for show. It allowed the many alien ambassadors on Babylon 5 to see that the Vorlons were a power to be reckoned with. This show of force would affect political interactions for years to come.
With the revelation of the true assassin, the Vorlon fleet was able to leave without losing face. They didn't have to blow anything up, and they didn't have to take Sinclair with them.
What about Kosh? The Vorlon government may have considered him expendable. More likely, these masters of order had the entire sequence of events planned out. They knew what poison would be used. They knew how many hours Dr. Benjamin Kyle would have to save Kosh. They knew that Lyta Alexander was on the station. The only event that was out of their control was Dr. Kyle asking Lyta to scan Kosh. I believe that the Vorlons would have studied Kyle's profile enough that they knew he would follow this course. Furthermore, although Kyle was already thinking of a telepath, Takashima the co-conspirator was the first to mention scanning out loud.
Only the Vorlons could have brought several disparate factions into unison to carry out this conspiracy. Only the Vorlons came out ahead. Only the Vorlons were the masterminds behind the conspiracy to frame Sinclair.