Jeremiah "Jemmy" MacKenzie was born in May 1770 to time traveler Brianna Randall Fraser. Owing to various circumstances, it was unclear at the time who Jem's father was; however, when Roger MacKenzie reunited with Brianna at Fraser's Ridge, he vowed to raise the boy as his son, regardless of his paternity. Several years later, a birth mark was discovered on Jem's scalp which appeared to be identical to one on Roger's scalp, finally confirming that Roger was Jem's biological father.
Jem is a time traveler like his parents, and has made at least three journeys through time. He has lived in the 1770s and 1978-1980.
Events of the Novels
Drums of Autumn
In June 1770, Roger finally arrives at the Ridge, vowing to take Brianna's child as his own, regardless of its paternity.
In October, Jem's name is discussed on the journey to the Gathering on Mount Helicon. His name is chosen for Roger's father Jeremiah Walter MacKenzie who died in WWII.
The Fiery Cross
In October 1770, Jemmy is christened Jeremiah Alexander Ian Fraser MacKenzie at the Gathering at Mount Helicon.
In October 1772, while Brianna and Roger are talking with Jemmy's grandparents Jamie and Claire, and Young Ian, Jem is playing with an opal that explodes after he proclaims it to be 'hot'. This confirms that he is capable of time traveling through the stones, just like his parents and grandmother.
A Breath of Snow and Ashes
In July, Jemmy is at River Run. Jocasta's body servant Phaedre notices a tall, blond Irishman who takes an inordinate interest in Jem, asking who his father was. Jem proudly proclaims his father to be Roger MacKenzie. Phaedre tells Roger about the incident.
In August, Roger whittles a toy car for Jem, calling it a 'vroom'.
In July 1774, Jamie helps Brianna move a large boulder in the stream; Jem and Germain point out a peculiar pile of charred bones, and Jamie suspects it is some sort of a charm.
In November 1774, Jemmy has lice and Jamie shaves the boy's head, revealing an unusual birthmark on his scalp that Claire says would be genetic. Roger shaves his head as well to show that he has a matching birthmark, confirming Jem's parentage.
In June 1775, Roger leaves the Ridge to travel to Edenton for his ordination. He leaves Brianna and Jemmy at River Run. In August, Brianna is kidnapped and delivered into the custody of Stephen Bonnet. Roger, Ian and Jamie find Brianna, who has escaped the house in which she was held. Having captured Bonnet, they leave the decision what to do with him to Brianna.
In April 1776, Jem's little sister Amanda is born. In June, Claire finds that Mandy has a heart defect which cannot be repaired in the 18th century. Jemmy's parents start making preparations for their time travel back to the 20th century.
In July, the whole family travels to Wilmington to witness the execution of Stephen Bonnet. They are also looking for gems to ensure a safe passage through a stone circle. While in Wilmington, the MacKenzies meet William Ransom who, unknowingly, is Brianna's half-brother and Jemmy's uncle.
On November 1, after Brianna and Mandy go through the time portal on Ocracoke, Roger allows Jemmy to make a choice whether to stay in the past with his grandparents, or to go with them to the future. Jem chooses to travel with the rest of his family.
An Echo in the Bone
In September 1980, Jem's family receives a box of letters from Jamie and Claire. One of the letters indicates that Jem knows the location of the gold that was once kept by Hector Cameron for Charles Stuart – it is "guarded by the Spaniard."
After two months in the village school at Broch Mordha, Jemmy catches a large rat hiding under the school's foundation and skins it. The school principal, Mr. Menzies, congratulates him and tells him not to do it again at school.
In early October, Jemmy says someting to another student in Gaelic, and one of the teachers violently grabs him by the ear and shakes him. Deeply humiliated, Jemmy calls the teacher names, again in Gaelic, and Mr. Menzies hears him. Jemmy receives three straps from the principal. The next day, Roger comes to school. Mr. Menzies explains that he was sorry to belt Jemmy, as he likes the boy. However, he didn't have a choice as other students understood Jemmy's offensive remarks, and Menzies needed to support the teacher's authority.
Jem and his sister Mandy find a stranger hiding on the property of Lallybroch. The transient tells them he is a Nuckelavee, a horrifying creature out of Scottish folklore. However, he is actually William Buccleigh MacKenzie who has accidentally come through the stones from the year 1782.
Written in My Own Heart's Blood
On October 30, 1980, Jemmy is being held by Rob Cameron, who wants the boy to show him where Jemmy's grandfather has hidden gold. A security guard finds Jemmy in a tunnel under Loch Errochty, but is shot by another man, presumably Cameron's accomplice.
The next day, while Jemmy and Mandy are staying at the Buchans', Rob Cameron arrives to ask Fiona questions about Craigh na Dun. Jemmy calls the police, but Cameron escapes. Ernie Buchan doesn't want to put his family in danger and decides to take Jemmy and Mandy back to Brianna.
Brianna stakes out her own house with a shotgun, as she believes someone is inside. Ernie arrives with the kids, and Brianna rushes to stop them from getting out of Ernie's truck. Two men come out of a house, and another truck with Rob Cameron arrives, and Brianna fights him to get to her children and keep them safe. The MacKenzies eventually get away safely with the help from Ernie and Lionel Menzies, Jemmy's school principal.
In November and December, Brianna and the children hide in America. With help from Joe Abernathy, they conduct experiments to see how far can Jemmy sense Mandy, and vice versa. Brianna also makes preparations to travel through the stone circle to find Roger, who is looking for Jemmy in the past.
On December 21, 1980, Brianna, Jem and Mandy go through the stones at Craigh na Dun and arrive in 1739. Short time later, Roger meets them outside of Lallybroch.
In early June 1779, Jemmy and his family arrive at Fraser's Ridge.
Stubborn, brave, and resourceful.
Jem strongly resembles his mother and grandfather, with red hair and blue eyes, as well as various hereditary mannerisms and expressions. He does, however, have a mole on his scalp in the exact same location that Roger does, behind the left ear and just above the hairline. At nine, he is tall for his age.
- Jeremiah comes from the Hebrew name יִרְמְיָהוּ (Yirmiyahu) which meant "YAHWEH has uplifted". This is the name of one of the major prophets of the Old Testament, the author of the Book of Jeremiah and (supposedly) the Book of Lamentations.
- Alexander is the Latinized form of the Greek name Αλεξανδρος (Alexandros), which meant "defending men" from Greek αλεξω (alexo) "to defend, help" and ανηρ (aner) "man" (genitive ανδρος).
- Ian is the modern Scottish variant of the name John.
- John is the English form of Iohannes, the Latin form of the Greek name Ιωαννης (Ioannes), itself derived from the Hebrew name יוֹחָנָן (Yochanan) meaning "YAHWEH is gracious".
- Fraser may be derived from Fredarius, Fresel or Freseau. Another suggestion is that the Frasers were a tribe in Roman Gaul, whose badge was a strawberry plant.
- MacKenzie is the anglicized form of MacCoinnich, a Gaelic patronymic name meaning "son of Coinneach". The personal name Coinneach means "handsome" or "comely".
- Age as of the end of Written in My Own Heart's Blood.
- Behind the Name: Jeremiah - Accessed 30 September 2014.
- Behind the Name: Alexander – Accessed 19 April 2015.
- Behind the Name: Ian – Accessed 17 March 2014
- Behind the Name: John – Accessed 17 March 2014
- Way, George and Squire, Romily. Collins Scottish Clan & Family Encyclopedia. (Foreword by The Rt Hon. The Earl of Elgin KT, Convenor, The Standing Council of Scottish Chiefs). Published in 1994. Pages 142 - 143.
- Behind the Name: Coinneach – Accessed 19 April 2015.