Bidam was Mishil's son. But Mishil abandined him after King Jinji refused to recognize Mishil as his queen. On that day, King Jinji was dethroned as King. Mishil revealed that the latesking's successor was his nephew (Deokman's father).
Bidam grew up in the mountains. He did not have any idea about his parents until he met Deokman and Mishil. He saw a lot of himself in Mishil. He then found out that he was Mishil's son. Mishil, did not recognize him as her own even before she died.
On the other hand, Bidam has fallen in love to Deokman. When they first met, he was not so gentle to Deokman. He even once tried to trade Deokman to sacks of herbs. But Deokman did not show him any cruelty even after she found out that she was the Silla Princess.
Bidam was so true to his feelings for Deokman. He did not have any doubt about it until he was screwed up by his own followers. They swayed Bidam. They made him believe that the Deokman lied to him. They made Bidam believe that Deokman trully wanted him to die for he was Mishil's son.
Bidam then planned to revenge.
Eventually, he found out that he was just used by his followers. He was so resentful. But was already on the bridge of no turning back. He has already been declared as public enemy and must face death.
Bidam died in the hands of Yushin, ten steps a way from Deokman. Before he died he granted the Queen's wish. That is to call her by her name "Deokman"