In Black Knight, Grandpa is an old man who has been looking after Sa-wol and his refugee friends for years. It is later revealed that he once lived a different life and played an important role in the creation of the Core District. Kim Eui-sung plays the role of Grandpa.
Grandpa is not related to Sa-wol or his three refugee friends named Useless, Dummy, and Dumb-dumb. However, Sa-wol’s three friends have been living with Grandpa, who takes care of them, as well as Sa-wol, like family.
After Seul-ah’s death, Sa-wol also goes to live with Grandpa and his friends. Grandpa is always there for the boys whenever they need him, and Seol-ah also thanks him for that. He also reassures a grieving Sa-wol that his sorrow will lessen with time.
He understands Sa-wol and supports him in pursuing his dreams. When 5-8 tells him that Sa-wol is a mutant, he asks 5-8 to let the boy live here with his friends, as he knows that Sa-wol is hurting and needs time to heal.
Grandpa keeps experimenting with different soils, and it is 5-8 who gets him different varieties of soil. It turns out Grandpa has known him since the refugee crackdown. Nine years ago, Grandpa was among the refugees who were resisting, but like 5-8, he survived.
Due to this, he knows that nothing good comes out when a crowd assembles. He refuses to go and watch the third round of the Deliveryman Recruitment Tournament on the big screens sent by the Cheonmyeong Group. This saves him and his boys from getting killed in the blasts that follow.
Later, when refugees start getting sick and dying, it is Grandpa who figures out that the vaccines are meant to kill the refugees. He informs 5-8’s group about the same, and the group then tries to stop the refugees from getting vaccinated.
Grandpa and Chairman Ryu’s relationship
Grandpa is now a refugee who often fixes machines for others, but he was not always a refugee. He has a scar on his hand that suggests that he also had a QR code like the people who live in General, Special, and Core districts.
When Chairman Ryu discovers his son’s crimes, he comes to meet Grandpa. It is revealed that the two worked together on the blueprint of the Core District, but Grandpa left before the Air Core was constructed.
It is not known why Grandpa left and became a refugee, but Grandpa does say that he would rather live as a refugee and suffer than move underground for air. Without him, it took Chairman Ryu five more years to build the Air Core, which delayed the construction of District A.
Grandpa also admits that if he was there, he would have destroyed the Air Core. He even asks Chairman Ryu to come back and live aboveground, as he believes it is still possible.
As he keeps growing plants using soil from different places, he tells Chairman Ryu that the soil is coming back to life the further south one goes. Chairman Ryu then promises him that the refugees will be allocated and given a place in the General District.
However, Grandpa’s hopes are dashed when the news of Chairman Ryu’s death reaches him. He then gives the blueprint of the Core District to 5-8 to allow him to take Ryu Seok down. He also gives 5-8’s group, which is being hunted by the authorities, a place to hide and prepare for the attack.
While the fact that Grandpa once worked closely with Chairman Ryu before he became a refugee is known, there is still a lot that is not known about Grandpa’s life.
Also Read: Ryu Seok: Black Knight character explained