A native of Mars, Jeffrey Michael Sinclair was born on Mars in 3rd May 2213, raised a catholic, he went as far as training as a Jesuit for 3 years before joining Earth force in 2237. After 3 years training he became a starfury pilot, following a family tradition that went back as far as the battle of Britain.
In 2243 Sinclair began a relationship with Catherine Sakai, this would be a somewhat unstable relationship, characterised by repeated breakups and reconciliations whenever the pair met up after being apart for a significant time.
In the Earth-Minbari war Sinclair led the 361st Tactical wing at the battle of the line. During this battle Sinclair would go missing for 24 hours, and when he returned the war would be over as Minbari surrendered. He would not know what had happened for years and this gap in his memory would haunt him and damage his credibility within Earth Force.
After the Earth-Minbari war Sinclair was assigned to an Earth Force base on Mars, it was here he met John Sheridan during the Mars Food riots in 2251. A couple of years later in 2253 Sinclair hired Michael Garibaldi as a private shuttle pilot, in order to help investigate covert activity on Mars.
During one such trip, the shuttle carrying Sinclair and Garibaldi crashed; their mutual struggle for survival caused them to form a strong friendship. Also, during this time they witnessed a shadow vessel digging out another buried ship. At the time however they did not realise the significance of what they saw.
Also during his time on Mars, Sinclair met Laurel Takashima, in order to help get her to play by the rules Sinclair promised to push for her promotion. During an interview with ISN Sinclair was somewhat frank and made some inappropriate comments; this lead to him being sent to a deep range outpost.
After his latest break-up with Catherine Sakai, Sinclair started a relationship with a free trader, Carolyn Sykes. However this relationship ended when Sinclair refused to leave Earth Force and join Carolyn as a trader.
On 9th March 2256 Sinclair was made Commander of the Babylon 5 station. This was quite unexpected as Sinclair was very low down on a very long list. However, the Minbari, who were co-sponsors and helped finance the station, vetoed every person until Sinclair’s name came to the top of the list. The job itself had many facets, with Sinclair not only being the commander of the station but also Governor of the 250,000 civilians and Ambassador representing the Earth Alliance.
Sinclair brought Takashima as his second in command, and Michael Garibaldi has his security chief. Early in 2257 an attempt was made on the life of the Vorlon ambassador, Kosh. Sinclair was framed for this attack, however it turned out it was a Minbari using a changeling net, before dying the Minbari told Sinclair ‘You have a hole in your mind’. This gave him some indication of what happened in the missing 24 hours but left him with more unanswered questions.
During the first year of operation Sinclair solved many problems. He approached things with ethical and moral standards which sometimes meant he sometimes clashed with members of his crew, However he was also very supportive, sitting Shiva with his second in command, Lt. Commander Susan Ivanova after the death of her father.
In July of 2258 Babylon 4 suddenly reappeared, the crew were rescued by Sinclair and Garibaldi.
Towards the end of 2258 Sinclair rekindled his relationship with Catherine Sakai and at the end of the year he proposed to her, but then the president was assassinated and everything changed.
Shortly after the assassination Sinclair was recalled to Earth, here he met with Rathenn, a member of the Grey Council. Rathenn revealed what had happened to Sinclair at the Battle of the Line. During the battle Sinclair had been captured and interrogated. During this interrogation the Minbari had used the triluminary to probe him. During this they discovered that Sinclair had the soul of a Minbari, and that the souls of Minbari were being born into Humans. In order to prevent what they perceived as harm to themselves, the Religious Caste brought an end to the war by ordering the warrior caste to surrender.
What Rathenn did not reveal was that Sinclair didn’t just have any soul, but the soul of Valenn, the Minbari who formed the Grey Council 1000 years previously.
Sinclair was appointed to the post of Earth Ambassador to Minbar on January 12th 2259. However, this was not the only reason for his appointment to Minbar. He also became leader of the Rangers (Or Anla’shock in Minbari), with the title Ranger One (Anla’shock Na). As well as being ranger one Sinclair also took the title of Entil’Zha. This was the first time a ranger one had used this title since Valen himself 1000 years previously. Sinclair began to recruit humans into the rangers, which up until that point had being an exclusively Minbari organisation.
In 2259 Sinclair learned that the shadows were going to exploit the time rift in sector 14. In order to prevent this he took 2 Ranger candidates, Marcus Cole and Catherine Sakai on a mission to prevent the shadows from completing their mission.
They succeeded in stopping the shadows; however Catherine’s fighter fell into the time rift and was believed to have been taken into the past.
In August 2260 Sinclair received a letter, written 900 years earlier by Valen. The letter instructed Sinclair to get help from Babylon 5 and Epsilon 3. Using this help he travelled back to 2254 where they stole the Babylon 4 station. Sinclair and Zathrus then took the station 1000 years into the past in order for it to serve as a base of operations in the first Shadow War.
During the journey through time Sinclair used the Chrysalis device to transform himself into a Minbari. This was due to the fact that the Minbari of the time would not have been able to accept the station in Human hands.
On arrival Sinclair was joined by 2 Vorlons and introduced himself to the waiting Minbari as Valen, Minbari not born of Minbari.
Under the leadership of Valenn, the Minbari were able to push back the shadows to their homeworld of Z’Ha’Dum. After the end of the war the separate castes still would not put the old feuds behind them. Valenn decided to shame them by forming the Anla’shock (Rangers) whose members gave up all ties to their caste in order to fight for all Minbar.
Valenn went on to form the grey council and he also established the cultural norms which would last for centuries. When the war ended the Rangers were given the task of watching for the signs of the return of the shadows. Valenn also made many prophecies (since he was Sinclair and from the future)
Valenn married and had children, from this point on Minbari and human DNA began to mingle. Due to persecution Valenn’s children had to leave Minbar, however later generations were able to return. Delenn herself is a descendant of Valenn.
Towards the end of his life Valenn wrote the letters that 900 years later would be delivered to Sinclair and Delenn. These were locked in 2 boxes on Minbar, with instructions not to be opened for 900 years.
Valenn’s actual death is something of a mystery, his body was never found.