On Saturday's episode, Claire finally realized why Mary Hawkins' (Rosie Day) name sounds so familiar. It turns out that the shy, British girl is destined to become Black Jack Randall's (Tobias Menzies) wife, and thus Frank Randall's direct ancestor. The connection not only confirms for Claire that Black Jack survives the attack at Wentworth Prison, but that he needs to live for at least another year for Frank to ever exist.
Letting a sweet girl like Mary marry a monster like Black Jack would only be a moral problem for Claire if she and Jamie hadn't set a goal for themselves of changing Scottish history. They are in Paris to stop the Jacobite rebellion and prevent the Battle of Culloden on April 16, 1746. (Culloden ended with a British victory and the end of Scottish highland culture.)
By stopping the rebellion, Jamie and Claire would save thousands of lives, allowing the men supposed to die on that battlefield (including Jamie and Black Jack) to continue living, thus siring more children and changing the future of Scotland. But the plan would change two centuries' worth of Scottish and British history, making it impossible to ensure that Frank's ancestral line remains in tact.
Claire's concern over whether Frank will be born 200 years from her current time period begs the question: How does time travel work on Outlander? The show hasn't set any specific rules or explicitly shown the consequences of what happens when Claire interferes with events or prevents specific deaths.
In many ways, Claire's journey this season resembles Jake Epping's (James Franco) dilemma on Hulu's time-travel series 11.22.63. In that series, Jake goes back in time to stop the assassination of JFK, but falls in love with Sadie Dunhill (Sarah Gadon), who is fated to die the same day as the president. Jake eventually learns that preventing JFK's assassination would lead to the apocalypse in present day. He must go back through the reset portal and attempt to save Sadie without interfering with the assassination, because even small changes to the past have large consequences on future events.
But the season premiere of Outlander revealed that Jamie and Claire's efforts to stop Culloden will fail and Frank still exists when she returns to 1945, indicating that Claire's presence in the past makes no impact on the future.
In that case, Outlander might work more like the early seasons of the Doctor Who revival, in which landmark events like deaths are set in stone. One of Rose Tyler's (Billie Piper) first trips back in time with the Doctor (Christopher Eccleston) was to try and prevent her father from dying, but every time she tried to save him, he died in an alternative fashion. Rose couldn't change that he died, only how it happened. If this is how it works on Outlander, Jamie and Claire's influence would be moot against the powerful tide of history.
At this point in Outlander, the Jacobite rebellion has a growing list of wealthy supporters and is getting dangerously close to having the support of the French king. If Bonnie Prince Charles (Andrew Gower) were allowed to continue on his current path, it seems as though he would be able to assemble the resources necessary to raise a successful rebellion. Will Claire's intent to save Frank affect the outcome of the rebellion (per 11.22.63 rules), or will the Jacobites fall because they are, and always have been, fated to do so?
The preferred option is allowing Jamie and Claire to have a real influence in their current timeline. Giving them agency provides a better plot and a more intriguing creative angle for the show. The problem is, if the Frasers truly have the power to change the future, Claire will need to decide whether it's more important to save Scotland (and Jamie) or to save Frank — and we already know she makes the wrong choice.
Outlander airs Saturdays at 9/8c on Starz.