Dive into your creative stream
You know what character in the Outlander series was shafted in the television show?
Duncan Innes. That's who. And it makes me really mad to think about the fact that this incredibly shy, loyal, hard-working, slightly-bumbling, flawed man was literally written down to nothing but a plot device to add drama between Jocasta and Murtagh.
Practically nothing exists of his backstory from the books, and none of the characters feel for Duncan in the show the way they do in the books. He's not a former inmate of Ardsmuir so he doesn't have any of the backstory with Jamie, nor the mutual respect that forms so much of their friendship in the books. He's not with the Frasers at all in S3 (Voyager), so he gets no time at all to bond with Claire and tell her his past of being a fisherman caught up in Culloden, and any of his visits he pays them in Drums of Autumn (S4) is given to Murtagh instead. He simply appears in s5 as nothing more than drama that doesn't need to be there, and the series writers even admitted that in the show Jocasta marries not for love for Duncan but out of fear of being hurt by Murtagh. The major difference shows in the exchange between Jamie and Claire in the episode 'Better to Marry Than Burn':
Jamie: It should be Murtagh at Jocasta's side.
Claire: If Murtagh isn't here today, then it's his own choice.
While in the books, while I wouldnt say it's true love between Duncan and Jocasta, there is mutual respect and fondness, and it's made very clear that Jocasta does choose Duncan of her own free will to finally marry for her own satisfaction and not by the machinations of others. What's more, Jamie gives his full blessing to the match, pleased to hear that Duncan has proposed marriage at the end of Drums of Autumn:
'"I've no claim on any of my aunt's property, Duncan-- and wouldna take it when she offered. You'll be married at the Gathering? Tell her we'll come, then, and dance at the wedding."'
There are so many other examples I could find in the books to further my case but I currently don't have the time to read through books 5 and 6 again looking for specific passages. So just know that Duncan Innes in the show is a pale imitation of the Duncan in the books, and I sincerely hope that we'll see a bit more fleshing out of his character in the upcoming season 6. He's not perfect by any means in the books, but he feels so much more real than he does in the show. I love Murtagh to bits as a character, but I feel like his survival after Culloden in the show takes a lot away from situations that happen later in the story, and certain characters, and adds a lot of unnecessary drama to an already dramatic story. Duncan is an unfortunate casualty in that way.