"Changeling" child born to English nobility in the 14th/15th century, kept hidden away in a room in Glamis Castle. Grows up and escapes into Highlands. Becomes a warrior in the same vein as William Wallace and Robert The Bruce. Fights for Scottish independence alongside his friends, a Scotsman named McNulty, a Norseman called Wulf, and a haggis with a heart condition.
There are rumours that the Sleagh Maith have bestowed magical powers upon him including the second sight. Other rumours state that Seánie Beith and his wife, Red Agnes, murder passers by and drag them off to their lair to loot and eat them, but this is widely considered to be English propaganda.
When he is finally slain, it is said that he is not truly dead - that his body was carried away by the fairies to heal and sleep beneath a certain hill, until such time that he is needed the most.
McNulty cannae wait and digs him up.