Dylan, the son of an alternative reality version of James Lethbridge-Stewart, was born in 1960. When he was nine, his father escaped Inferno Earth with him (unfortunately, his mother, Rachel Lethbridge-Stewart (nee Jensen) was killed by Axonite-infected RSF troops). The temporal differential brought to the Brigadier's Earth in 1959. James kept Dylan closed off from society, in an attempt to keep him safe. Dylan adopted the name "Simon Gore", after his father's alias, James Gore.
At nineteen, in October 1969, his father gave Dylan his first mission: to befriend Owain Vine, and wait until the Great Intelligence manifested in him before bringing him back to the Vault. (PROSE: Night of the Intelligence) Dylan first met Owain in New York, where the Great Intelligence once again returned. There was an immediate attraction between them, and they quickly bonded. After a Yeti attack, "Simon" disappeared. Dylan kept watch on Owain, and reported back to his father. (PROSE: Times Squared)
Over the following months, Dylan kept track of Owain, watching him from a distance. He found himself feeling jealous of the new friends Owain had made, but knew he couldn't involve himself. He had a mission, and his father's control kept him in check. He was there on Santorini, and was the one who orchestrated the attempted kidnapping of Owain. (PROSE: Blood of Atlantis)
In 1970, Dylan was sent to meet Owain in Japan, and they kissed immediately upon being reunited, much to Dylan's surprise. After the Great Intelligence began to manifest, Dylan had him taken to Level 4 of the Vault, where his father planned to tap into the dimension where the Intelligence resided. Dylan was torn, however, because he had developed a deep connection with Owain. As a result, when troops from Fifth Operational Corps came to rescue Owain, he helped them. Dylan and Owain discussed their relationship, and ultimately settled on being "cousins". In reality Owain was the reincarnated soul of the James of Owain's world - a boy that, has he lived, may well have fathered Dylan in the real world too. And yet, despite that, they were not technically blood relatives. Later, Brigadier Lethbridge-Stewart, Dylan's uncle, finally embraced Dylan, and sorted out official paperwork so that he existed officially in the real world as Dylan Lethbridge-Stewart. After this, he and Owain opted to resume their travels. (PROSE: Night of the Intelligence)
Months later, during the summer of 1970, they came upon the dream eggs in Australia. Dylan had become somewhat jealous of Owain's company, and didn't care for bringing other people in. He especially grew concerned when it became clear that the dream eggs were connected to events in Scotland - he was worried it would attract the attention of his father. Nonetheless, convincing Owain to hand things over to Lethbridge-Stewart when he arrived, he agreed to explore with Owain. They found a damaged egg, which momentarily took over Dylan.
When the egg was destroyed, Dylan fell into a coma. As a result of this, Owain continued to assist the Brigadier in Australia. Once the eggs were destroyed, Owain, now on the astral plane, visited Dylan in his dreams to say goodbye. This awoke Dylan, who passed the message on to Lethbridge-Stewart. Dylan returned to Scotland. (PROSE: The New Unusual)
Due to his young age when he crossed realities, his quantum signature locked onto the new reality when he reached puberty. As a result, when the Inferno Earth began its death throws in 1974, he did not feel its pull like his father did. After his father's death, Dylan was the only denizens originally from the Inferno Earth on the real Earth. The Brigadier called Dylan on the phone, to tell him about James Gore's death. (PROSE: Ashes of the Inferno)