A native of Mount Desert island, Longfellow is old enough to remember the days when the radioactive fog covered almost the entire island. His indomitable will and fit physical structure still manage to keep up with his old age.
Old Longfellow is a seasoned hunter who can recall a fairly large portion of the region's history; from desperate struggle to prosperous hubris. Longfellow is a veritable legend in Far Harbor circles and one of the few guides capable of guiding a person safely through the fog. His age and experiences made him cynical and he hits the bottle of whiskey a bit too often in recent years.
Longfellow deeply hates the Children of Atom. When he was a young man, he was in a romantic relationship with a girl named Hannah and the two had planned a future together. The cult's followers attacked the pair at their hideaway deep within the fog and abducted Hannah. Left for dead, Longfellow eventually made it back to civilization. It took him two months to recover from his injuries and by then it was too late for Hannah. The Children's zealots had brainwashed her mind and converted Hannah to their ways. Hannah was pregnant, but suffered a miscarriage due to the radiation she worshipped and was exposed to, claiming it was "Atom's will" for it to have happened. Hannah afterwards fell victim to the insane trappers that roam the Island. Longfellow became an embittered shell of a man, mostly regretting the death of Hannah and his unborn child.
Longfellow is a heavy drinker, often asking if the Sole Survivor can stop for a drink or, when trading, ask if he can be provided with alcohol. He will even openly state that he will celebrate his death with a final toast (if the player kills him).
Despite the fog driving most people insane (such as the Trappers), Longfellow seems to be quite sane and reasonable—though he often claims his limbs are stiff and his bones ache due to the exposure of the fog.
Longfellow openly dislikes the Children of Atom; disliking if the Sole Survivor joins them and when talking with DiMA when he talks about the possibility of there being peace with them, he openly states he would enjoy fighting them. Interestingly, he disapproves if the Sole Survivor suggests to spare or reason with Sister Gwyneth when talking to Grand Zealot Richter in The Heretic mission. This is possibly because he dislikes sparing a Child of Atom, even if that is the order of another Child of Atom.
When Idolized, he will reveal he always wanted a son and/or daughter to teach what he has learned to them.
He will become hostile if Far Harbor is destroyed.
He is not resistant against radiation.
He will sometimes sing the traditional Irish songs "Wild Rover," "Molly Malone," and "Jug of Punch" when idle.
Sometimes when picking up junk items, Old Longfellow will jokingly question why the Survivor would need something three times older than himself. Since the events of Far Harbor take place two hundred and ten years after the Great War (which would be around the same time the last of most pre-war junk was made) it would put him at around seventy years old.
While utilizing power armor does not negatively affect Old Longfellow's opinion of the player character as it does for Strong, he will state he's not overly fond of powered armor because "It's too damn loud to hunt in".