Despite being half-Orlesian, he joined the rebel cause under Prince Maric during the Orlesian occupation of Ferelden. He fought for the Army of the North under Bann Angus Eremon alongside his friends Bryce Cousland and Rendon Howe, taking part in the Battle of the White River, the most catastrophic defeat of the entire occupation from which only fifty rebel soldiers escaped.
During the battle, Rendon was gravely wounded and had to be dragged off the field by Bryce and Leonas. When Bann Angus finally sounded the retreat, they carried their injured friend to a freehold in Redcliffe and stayed with him for nearly a month while the other survivors left to find the Army of the South. When Bryce and Leonas finally rejoined with the army, making the journey on foot, Prince Maric personally awarded them medals of valor. Rendon remained in South Reach, being tended by Leonas' sister, Eliane, a talented physician and herbalist.
When Rendon was made Arl of Amaranthine, Eliane traveled with him; he proposed to her after a year. Leonas had become concerned by the changes in his friend's behavior since the battle and tried to prevent the marriage. When Howe told him that he needed Eliane for her dowry and connections, he severed all contact with Howe and his sister and refused to witness their vows.
After the defeat of Ferelden's army at Ostagar, the darkspawn horde moved north. In this time of need, the village of Lothering, which belongs to his Arling, was left leaderless with no formal evacuation plan. He goes on to mention to Bann Alfstanna that South Reach has been overrun by darkspawn.
Once the Landsmeet starts, he can be found in the Gnawed Noble Tavern, conversing with Bann Alfstanna. After Arl Rendon Howe is killed in his own estate, Bryland makes it clear he does not feel any regret at the death of his former comrade. During the Landsmeet gathering, he will always support the Warden. If the Landsmeet devolves into a brawl, Bryland and his troops will back the Warden up. Bryland is armed with a greatsword resembling Ageless and is a two-handed Warrior.
- "Habren has done nothing since we've arrived except spend coin on herself. If we stay in Denerim much longer, I'll have to send her to a cloister."
- "Rendon Howe was no friend of mine. The boy I knew... died at the Battle of White River."
- "That he didn't die years ago is the only thing worth mourning here."
- "Some of us are curious, Loghain, about what precisely happened at Ostagar."
- "South Reach stands with the Grey Wardens."
- The toolset also states that Leonas studies art and history in an effort to make sense of the things he has done.
- According to the Dragon Age: Origins: Prima Official Game Guide, his first name is Gareth.