He was born on 24 August 1198 to William I and Ermengarde de Beaumont, inheriting his father's red hair and ambition. The first trouble came one month after his coronation in December 1214, when the MacWilliams and MacHeath clans revolted. The MacWilliams were descended from Duncan I, and had been excluded from succession by David I, who adopted the English tradition of primogeniture. Their attempt to take the crown back was quickly put down by loyalists.
Alexander had been knighted a year earlier by King John; the Treaty of Falaise required that he spend time in his youth being educated at the English court. He and his status were known to the English barons; when they rebelled against John in 1215, Alexander joined them. John retaliated by sacking Berwick-on-Tweed in Northumberland, where the king had a mint. When the Magna Carta was drawn up for John to sign, reducing his power and granting more autonomy to the barons, Clause 59 was added for Scotland:
We will deal with Alexander, king of Scots, concerning the return of his sisters and hostages, and his liberties and right, in the same manner in which we deal with our other barons of England, unless it should be otherwise under the charters which we have from his father William, former king of Scots. And this will be by judgment of his peers in our court.
John later rejected the document he had been forced to sign, and took his army north to punish Scotland and “hunt the red fox-cub from his lairs”; he had to return south quickly, however, when he learned that the barons had invited French King Louis VIII to accept their homage and take John's place. (They gave up on Louis when John died and the child Henry III became king with a regency council.)
With Henry's regency supporting Magna Carta, Alexander could turn his attention from his relationship with England to his relations with his own neighbors, who until recently were independent until William I subdued them. Alexander also had parts of "his" realm ruled by the Norse and Norway. How he dealt with them is a story for tomorrow.