Supernatural introduced Jesse Turner (Gattlin Griffith) back in season 5, but what became of the character and why did he never return? Supernatural featured a plethora of recurring and one-off background characters during its 15-year run, so it's natural that some would be forgotten along the way. But Jesse's storyline seemed to foreshadow something big being in store for him down the series' pipeline — and yet, he only ever made the one appearance.
Jesse's story occured in Supernatural season 5, episode 6, «I Believe the Children Are Our Future.» Although he looked just like any other human, Castiel revealed the child was actually the Antichrist — otherwise known as a Cambion, an entity conceived when a virginal mother is possessed by a demon — and had powers beyond their understanding that could bring about the end of the world. While Castiel was resolved to kill Jesse and prevent any evil the boy might commit in the future, the Winchesters believed his human half gave him the capacity for good. Instead of killing Jesse, they gave him the chance to disappear.
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After Jesse's introduction in Supernatural season 5, he was indeed never seen again. Where the young half-demon, half-human character ended up is a complete mystery as far as Supernatural canon goes. The greatest running theory is that Jesse ended up in Australia. When he transported himself away at the end of his sole episode, he was looking at a poster adverstising the country. Castiel confirmed in the episode that Jesse had the capacity to pull off such a feat. In the production draft for Supernatural season 15, episode 13, «Destiny's Child,» Dean suggests the alternative Winchesters travel to
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