A What if Scenario, where King Alexander III of Scotland's son Prince David does not die in 1281, and instead is alive when his father dies in 1286.
David is crowned King at Scone on the 15th April, 1286 and instead of having a regency immediately assumes command with some trusted advisers. David tired of seeing the influence Norman England has had on his country and people, begins slowly reintroducing Gaelic ways, such as Gaelic music and songs, the Gaelic language etc. He also sells of the lands his family holds in southern England and saves the money made in an attempt to prepare for war.
David marries Isabel Bruce of the Bruce family one of the more powerful lords in Scotland on the 1st of May 1286, solidifying an alliance with the Bruces and promising to give them a prominent part in his plans for Scotland's future. Their first son named Kenneth is born on Feburary 12th 1287.
When word comes to London and to Edward I of David's new laws, Edward is at first impressed and then concerned, and when southern Scottish nobles send word to London asking for help, Edward sends a missive to his nephew, telling him to swear fealty to him as his overlord. It is also around this time that the Pope fearing a pagan revival in Scotland begins making sermons about the heathen scots, and so a fear of war grows. Edward promises to protect David from the Pope and any army he might send for return of fealty.
David stubborn and confident refuses and sends back the head of Edward's envoy, proclaiming that he needs no help from a norman. He then declares his intention to reclaim Northumbria for Scotland. War begins with England in 1290