In Tekken 2, Baek first appears as Marshall Law's Stage Eight sub-boss. The reason for this is because Baek Doo San went on a rampage after accidentally killing his father. Baek destroyed many dojos, including the one owned by the Laws. In Tekken 3, Baek is not present but he was, in a sense, replaced by his pupil, Hwoarang.
Baek is described in the second game as evil due to being traumatized for killing his own father in their sparring session and was responsible for destroying dojo including Laws. This behavior is soon subsided in his ending where he forgives himself for killing his father.
However from Tekken 5 and onwards as the master of Taekwondo, Baek shows as being serious and a good man but being a strict person especially to his student Hwoarang. He also disapproves Hwoarang for street hustling as seen from his ending in Tekken 5. He is also shown to be a risk taker as seen in his Tekken 6 ending where he saves Hwoarang at the cost of his life. Therefore his sorrow and his traumatized past still remains within him as he still remembers how he killed his father in his ending in Tekken Tag Tournament 2.
Baek Doo San, a master of Taekwondo, is the son of a former Taekwondo champion.
During his childhood, his father received a career-ending injury. Devastated, his father turned to alcohol and became a heavy-drinker, which ultimately led to his incarceration.
Plunged into a life of poverty, the young master's family was forced to deal with hard times, and just when things looked as though they couldn't get any worse, his mother disappeared, leaving him and his siblings alone. Not too long after that, his father escaped from prison to assist the family, but due to the deprivation of proper nourishment, Baek mistakenly killed his father, a man he respected above all else.
The frightening experience left him traumatized, driving him crazy every time he saw blood. When the police found him, they took him into their care and raised him.
Years later, he found himself walking the path of his late father, a Taekwondo master, and champion, but unfortunately, a person knowing the truth about his father's death threatened to go public with the truth of his past if he didn't destroy his blackmailer's competition.
He became a bodyguard for Kazuya Mishima.
The attack on the martial arts school Marshall Law instructs at took place while the school's instructor was away; a confrontation between Baek Doo San and Marshall Law is inevitable.
Ending Description: Baek is seen sitting on a bench outside a park. He takes out a locket containing a photo of him and his father. Baek reminisces about his training sessions with his father, remembering the great person he was and how much he loved him. Remembering his father for the man he was, Baek finds peace within himself and he forgives himself for killing his father.
According to the Tekken 3 storyline, Baek was presumed dead after encountering Ogre, the fictional Aztec God of Fighting. One of his closest students, Hwoarang, entered The King of Iron Fist Tournament 3 to exact revenge for his master's death and to also have a rematch with Jin Kazama, the only fighter who had ever fought him to a draw.
Several male characters from the Tekken 2 lineup returned in Tekken 5, including Baek. According to the game's storyline, his encounter with Ogre had left him in a coma; not dead as initially presumed. He woke up over a year later; after his student Hwoarang had already competed in The King of Iron Fist Tournament 3. Baek then began teaching Taekwondo at military bases. Hwoarang was drafted into the South Korean Military, but he ran away to compete in The King of Iron Fist Tournament 4. When he was arrested by the South Korean Military Police, he was informed that Baek was alive. Baek decides to enter the King of the Iron Fist Tournament to test his student's skills.
Ending Description: When his student Hwoarang is about to fight three thugs in the street, Baek immediately calls his student after seeing him doing street hustling and he angrily disapproves his actions as one of the thugs knock Hwoarang with a single kick. The three thugs are soon to confront Baek, Hwoarang attempts to stop them which Baek becomes angry towards them as he quickly defeats them in proccess as Hwoarang watches. Hwoarang shrugs as Baek strictly drags him while walking away.
Baek entered The King of Iron Fist Tournament 5, along with his disciple, Hwoarang. However, Baek withdrew from the tournament when he found out that Hwoarang lost to Devil Jin, and he was seriously injured. Baek then rushed to the hospital to visit Hwoarang. Although Hwoarang's condition wasn't considered as something serious after his treatment, Hwoarang wouldn't wake up, and Baek started blaming himself for being an inadequate instructor.
It took Hwoarang three days to regain consciousness. They discussed the details, and Hwoarang told Baek that he not only has to recover, but he has to strengthen himself even further. Baek sensed his strong will and his unprecedented modesty, and hence he decided to teach him everything he knows. Baek and Hwoarang returned to Korea, and endeavoured to practice intensely. Eventually, the announcement of The King of Iron Fist Tournament 6 came from the Mishima Zaibatsu, and Baek decides to enter the tournament one last time to widen his personal experience-collection.
Ending Description: Baek has defeated Azazel. Hwoarang then comes in, asking if he is all right. As soon as he gets up, so does Azazel. However, as Azazel is about to attack, Baek finishes him off by front-kicking him. Azazel's orb broke and he broke to pieces. However, Baek falls to the floor after risking his life to save Hwoarang, while the latter cries for his master to not die (not knowing that he was too late).