Laying down a delicious mystery can add a rich depth to a show. It can revitalise a story or add shade to a character's history. A mystery can be inexplicably surprising or deceptively simple in its resolution, but what if we never get an answer to a compelling enigma? Sometimes that can work for a story as not every question needs an answer. Sometimes the tantalising unrealised possibilities might be better than a concrete definitive conclusion.
But there are those mysteries that continue to nag at us long after the credits have rolled, knowing that shifting studio priorities mean that we might never see an answer after a cancellation of an intriguing show. While big franchises like Star Trek and Doctor Who might be able to go back and have a try at untangling those dangling plot threads, other shows aren't so lucky. And instead we're left to ponder what could have been when it comes to puzzling plot points and unresolved narratives.
So, with that in mind, here are ten mysteries from science fiction television shows that we'll likely never know the answers to.
10. Annie (Lost)
More than ten years after it finished, there are still questions being asked about Lost. So let's just focus on one small mystery: Annie. Annie appeared in only one episode (The Man Behind The Curtain) in the flashbacks for Benjamin Linus.
Ben's backstory was compelling, he arrived on the mysterious island with his alcoholic father in 1973 and was miserable. His only friend was Annie, a small girl that arrived around the same time. Unlike his father, Annie remembered Ben's birthday and gave him a small doll of herself. After that, we never saw Annie again.
What happened to her?
We know that Ben kept hold of that doll, tenderly referring to it as 'a birthday present' when asked about it. But she didn't appear to be amongst the Dharma Initiative folks that were killed by the Others in 1992. Ben made a point of closing Horace Goodspeed's eyes, but didn't seek out Annie. So had she left the island by then?
Some speculated that Annie would turn out to be Kate (since she had used the alias Annie while on the run), but this was not the case. While Lost had so many unanswered questions, Annie remains one of the most intriguing. Indeed, actor Michael Emerson said that Annie's absence from the rest of the show was a missed opportunity.