Brianna Ellen Randall Fraser MacKenzie is the second daughter of 18th Century laird Jamie Fraser and his time-traveling 20th-Century wife, Claire Fraser. Brianna was raised in the 20th Century by Claire and her husband, Frank Randall.

Brianna was unaware of her parentage until after Frank's death, during a trip with Claire to Scotland, at which time the truth was revealed to her.

During that Scottish trip, Brianna also met her future husband, Roger MacKenzie. When Claire returned to the 18th Century to be with Jamie, Brianna soon followed, and in her wake Roger.

Brianna and Roger have two children, Jeremiah "Jemmy" and Amanda "Mandy."

They currently reside on the family home of Lallybroch after finding it for sale after their return to the 20th Century for reasons associated with Mandy's health.