BS Fire Emblem
Prior to BS Fire Emblem, Hardin lived a simple life as the heir to the Aurelian throne. Despite his position he was angered by the plight of his people, some Archanean nobles were using his country as a slave capturing grounds, a huge violation of the Aurelian sovereignty. Working with his brother, Hardin fought the Archanean nobles and freed all slaves in Aurelis. After freeing the slaves, Hardin met former slaves Wolf, Sedgar, Vyland, and Roshea; they pledged their lives to Hardin, and became soldiers in the army.
After Medeus attacked Archanea, King Michalis ordered the Macedon army to invade Aurelis. The Macedonians were able to capture Aurelis Castle, and Hardin, his brother, and his soldiers retreated to the southern fortress. Hardin was no fool, he realized that his army could never win a face to face fight with the Macedonians, so he employed guerrilla tactics against the Macedonians and slowly lowered their numbers.
When some of the Macedonian soldiers left the army, they started pillaging the villages of the Aurelian country side. Unable to ignore this brutality, Princess Minerva joined forces with an incognito Hardin to stop the raids. When the battle was finished, Hardin and Minerva found a mutually respect for each other. When the Macedonian army tried to capture Hardin, Minerva ordered them to stop and she left the battle thinking about her strange ally.
As the war progressed, General Camus of Grust was ordered to hand Princess Nyna over to Medeus. Knowing that she faced certain death, Camus arranged for Nyna to be spirited away to Hardin's fortress in Aurelis. Camus was able to successfully guard Nyna, but he himself was captured by Medeus and imprisoned for treason. Nyna joined forces with Hardin, and together they called for allies from across the land to join their fight.
As time passed, the Aurelian army began to lose against the Macedonian forces. When Prince Marth arrived, Hardin quickly joined forces with him and together they forced the Macedonian army out of Aurelis for good. Hardin asked Marth to lead the army, believing him to be a honest and trustworthy individual. Hardin accompanied Marth as his second in command, and together they liberated the continent and defeated Medeus.
After the war, Bishop Boah asked Nyna to choose a husband to help rebuild Archanea. Knowing that Marth was in love with Princess Caeda, Nyna asked Hardin to marry her, and he became the 24th king of Archanea.
Mystery of the Emblem
Hardin had fallen deeply in love with Nyna, and quickly accepted his role as king of Archanea. Unfortunately, Nyna was still in love with General Camus, even after knowing that he had fallen in battle against Marth. Boah ordered Nyna to hide her feelings for Camus, but Hardin eventually discovered them. Heartbroken, Hardin retreated to his chambers refusing to see anybody, the evil pontifex Gharnef took advantage of his mental state. Posing as a merchant, he gave Hardin the Darksphere, a powerful magical artifact which corrupted Hardin's mind, and placed him under Gharnefs control.
The corrupted Hardin declared himself emperor, and had Nyna confined to her room. Plotting with the avaricious General Lang, Hardin placed a trap for Marth and his other former allies. He framed General Lorenz of starting a rebellion, and ordered Marth to subjugate Grust and Macedon. With Marth occupied, he attacked Altea, and had the country practically annihilated. Declaring Marth an enemy of Archanea, he had the armies of Archanea, Khadein, Gra, and Aurelis harass Marth across the continent leaving a path of destruction in his wake.
Eventually, with Gotoh's aide Marth acquired the Lightsphere needed to overcome the power of the Darksphere. Marth attacked Archanea and fought Hardin one on one. Defeated, Hardin returned to normal and begged Marth for forgiveness. Asking Marth to take care of Nyna, Hardin thanked Marth for saving him and died from his wounds.
Hardin appears in Fire Emblem: Awakening as an allied NPC unit on the third DLC map, helping Prince Marth in his war against Prince Celice of Jugdral. Afterwards, Hardin appears in the next map as an enemy allied with Marth and Alm, at war with Sigurd. Following that, Hardin appears in Ephraim's DLC map, as an enemy unit allied with Camus. Interestingly, this is the first time that Camus and Hardin have appeared in the same army.