Harry was the second son born to Sir Joseph lord of Brechin but the first born inside wedlock, due to this fact Harry would one day succeed his father. His older half brother Paul resented this and the two were educated differently by their father so that the hostility shown between them particularly by Paul could be abated. Harry was given the best education money could buy that befitted someone of his position. Harry attended the finest centres of learning throughout Scotland however in order to advance his skills in swordsmanship he was sent to France to attend the school of the renowned sword master Charles Valois. It was here he met Sir Andreas of Thurso, both of these young men showed great qualities. Harry returned home frequently but came into more and more disputes with his father regarding the de Brechin's allegiance. The de Brechin's had always supported the Comyn/Balloil faction, Sir Joseph was related to the earl of Buchan John Comyn, however Harry saw this as a lost cause after the humiliation of King John Balliol's reign and much preferred the qualities demonstrated by Robert the Bruce. This friction had began earlier when Sir Andreas had persuaded Harry to join Andrew de Moray at the battle of Stirling Bridge, but the cause seemed lost after the defeat of William Wallace at Falkirk. Due to the fact Harry was still a young man his father forgave him but as time went on he could see his son was not for turning.

A few years later Harry was working for Robert the Bruce were Harry was gaining valuable information about English plans from his counter part at the English court Henry Fennes. Harry had learned of his fathers death but he knew things would not be easy for him, the Earl of Buchan would not be pleased to learn that this de Brechin pledged his allegiance with Robert the Bruce and no doubt Sir Harry's half brother Paul would not take to kindly to hearing of his brothers new position. Sirs Harry and Andreas had business in France and they took the opportunity to visit their old sword master  Charles Valois, it had been a few years since their last visit and sir Harry was intrigued by Charles daughter Paulina for she had grown into a fine woman. After a short romance they were married in the old town of Prague, Sir Harry spared no expense even hiring one of Europe's foremost cooks Emilea Emhari. A few years later Sir Harry would repay Emilea by inviting her to cook for one of Sir Harry's allies Sir Aidan de Culter's wedding.  On his arrival back in Scotland with his knew wife Sir Harry had learned that Henry Fennes had been made a prisoner by Piers Gaveston, Sir Harry discussed the matter with Andreas and Aidan and agreed that a rescue attempt would be made. Sir Harry sent a mercenary in his service David de Brownhill who had experience in dealing in such matters; Sir Aidan suggested sending Tristan Moir who had been working as a go between from Sir Aidan and Henry to accompany David on their attempted rescue.

Upon David's return Sir Harry was told by David of Tristan's treachery and how he had tried to kill both Henry and himself. A few days later Tristan arrived back in Scotland and Sir Andreas had him arrested and imprisoned.  Sir Harry suspected not all was as it seemed, he talked with Sir Aiden who suggested using the powers of the church to investigate the matter, Sir Aiden contacted his old mentor Michael Beckett who managed to get a confession from David that it was he who was the traitor but Paul Brechin was behind it all hoping to show Sir Harry as a traitor and in the event of the De Brechin lands becoming free and defaulting to the Earl of Buchan it would be Paul who the Earl would look to take to as a reward. The plan now exposed allowed Sir Harry to now hunt down his half brother. However, this had to be put to one side, as conflict between Scotland and England had grown. Robert the Bruce now required all of his supporters to take up arms in his name. Sir Harry, Aiden and Andreas decided to send their womenfolk to Kildrummy castle for safekeeping under the watchful eye of one of Sir Harry's trusted servants - Alan of Harris. It was to prove to be a wise choice, for while on campaign Sir Harry had learned of his half brothers attack on Kildrummy and also that had it not been for Alan, many a noble lady would have taken as a prisoner and used as hostages against Robert the Bruce.

During the rout of Bannockburn Sir Harry had attempted to stop the bloodletting as the English fled.  Where he was confronted by Paul Brechin on the field, Sir Harry moved towards his half brother but before they came together Sit r Andreas rode in between them and Killed Paul with a single blow. This is not the conduct of a night and both Sir Harry and Sir Andreas agreed not to let anyone know of the events that had just taken place.  Content in the fact he had been justified in the killing of his half brother, Sir Harry returned home.  Rejoined with his beloved wife, they settled down to a relatively quiet life.  Troubles flared again, after the death of King Robert the Bruce, but by now Sir Harry was too old to fight, he was saddened to hear of the death of his great friend Sir Andreas at Haliedon Hill and through his wife ensured that Andreas son - John Mackay received the best tutoring.