Margaret's vision produces the following information: "When twice 1,200 moons have coursed, 'tween man's attack and woman's curse, and when the issue is cut down, then will a Scotsman wear a crown.” To put it simply, it's Brianna, the baby who was born 200 years after she was conceived.
Starz's version of the prophecy is, "A new king will rise in Scotland upon the death of a child that is 200 years old on the day of its birth." With the knowledge that Brianna was conceived in 1746 but born in 1948, Geillis decides to travel back to the future to murder Brianna.
Brianna is the 200-year-old baby
Brianna was conceived in 1746 between Claire and Jamie. Claire then took a trip through the stones and gave birth to the baby in 1948. She is technically 200 years old at the time of her birth, even though she is definitely not a case of Benjamin Button.
William Buccleigh MacKenzie is the illegitimate son of Dougal MacKenzie and Geillis Duncan, and was raised by William John and Sarah MacKenzie. He and his wife emigrated to America with their infant son, Jeremiah.
Some think Jamie's spirit (but not his body) traveled to through time to guide Claire to him; others suggest Jamie had a near-death experience after the Battle of Culloden, and that's why his ghost is 25 when he appears to Frank.
For now, though, it appears both Fergus and Marsali aren't time travellers with actors Lyle and Domboy addressing this in an Instagram live Q&A from earlier this year.
Diana Gabaldon has confirmed there is no possibility that Jamie Fraser will time-travel into the future and live out his life at Lallybroch.
Roger is a descendant of Geillis and Dougal's son. Roger has Geillis's green eyes and inherited her ability to pass through the stones. He meets her in 1739, having traveled through time in search of his son, Jem.
The simple answer is no. Claire and Jamie don't have any more children after Brianna. Claire heads through the stones while pregnant with Brianna at the end of the second season/book. She spends 20 years in the 20th century, and she and Frank don't have any children together.
And Roger is a direct descendent of Geillis and Dougal MacKenzie's illegitimate son, William Buccleigh MacKenzie. Buck and Roger can both time travel thanks to Geillis. And that comes into play in Outlander books 7 and 8.
In Scotland in 1968, Claire tells Roger Wakefield that Geillis Duncan was his ancestor and that she was burned as a witch in 1743.
Fergus apparently knows Claire is a time traveler in Outlander. Diana Gabaldon mentions now and then on social media that Fergus knows Claire is a time traveler. This is something that happens off-book in the series. Fergus and Marsali have both learned the truth, which is important for later books.
Margaret's vision produces the following information: "When twice 1,200 moons have coursed, 'tween man's attack and woman's curse, and when the issue is cut down, then will a Scotsman wear a crown.” To put it simply, it's Brianna, the baby who was born 200 years after she was conceived.
Later, after Claire has returned to the Ridge, she is confessor to Allan Christie, who explains that he was the one that fathered Malva's child, and then murdered her.
Dwarfism is a genetic mutation. Sometimes it's in the sperm and sometimes it's in the egg. Nobody really knows why this genetic mutation happens (and why it doesn't happen in every child from the same couple), but it's got nothing to do with what happened to Marsali.
The young Malva then later claimed Jamie was the father of her baby, and was eventually found dead in the Fraser's vegetable patch. In a particularly harrowing scene, Claire tries to save the unborn baby but is tragically unable to.
Jamie marries Claire to keep her from falling into the hands of the evil Captain "Black Jack" Randall. They have one child, Faith, who doesn't survive birth; an adopted son named Fergus; and a daughter, Brianna.
The Fiery Cross
Claire and Jamie care for her and give her goat's milk, keeping her warm as they bring her into Brownsville. Once in Brownsville, they find a nursing mother to feed the child, and Richard Brown makes the executive decision to take her in and raise her as his.
Roger volunteers for this dangerous mission perhaps in large part to prove himself to Jamie Fraser, to prove to his father-in-law that he is fit to be a captain in the militia. Of course that all goes terribly wrong and he is “accidentally” hanged by Governor Tryon, after being mistaken for one of the Regulators.
Later, Geillis and Claire meet again, although Claire had believed Geillis to be dead. Geillis reveals that, since she was pregnant, her death sentence was postponed but after she gave birth, her lover Dougal MacKenzie arranged for her escape.
Roger and Brianna are distantly related in Outlander
Brianna is the child of Claire and Jamie. Jamie is Dougal's nephew. This is important to remember as it does mean that Brianna and Roger are both related to Dougal MacKenzie. Roger is not the son of Geillis and Dougal.
“I curse you. I curse you with knowledge, Jack Randall. I give you the hour of your death. Jonathan Wolverton Randall, Born Sept 3rd, 1705, dies…” she whispers in his ear, and suddenly he knows that she's telling him the truth.
Jamie denies having slept with her, but the damage to his and to Claire's reputation is done—and the bond between the Frasers and Malva is severed, until just a few weeks later, when Claire finds Malva murdered in the garden.
Roger is the father of Bree's baby in Outlander
She worried at first, but Roger was able to calm the fears. There was nothing sinister about that mole. Roger has one, and he makes a note that it's hereditary. This is all the confirmation everyone needs.