Here's my theory on why the cliché sick plot was suddenly bought up; maybe it's for the parents approval, since the father didn't take the death of jun's friend it will be like a reality check for the father, and the mother wont be able to hold jun back now that he has leukemia, the mother will focus on his happiness. So he might recover from leukemia and his parents will let him stay with ra-ra
the promo for the next episode looks crazy what are everyone's theory on what's going to happen? do you think rang will try to kill ji a? i think he'll try but give up in the end. also killing the gatekeeper might just be yeon's plan to get imoogi. he wont actually give her life
if u ask how her mom survived, her mom as uk was not normal so we can't really relate or think from her view, she must have waited a long time simply to take revenge because that's just her nature.
maybe it's for the parents approval, since the father didn't take the death of jun's friend it will be like a reality check for the father, and the mother wont be able to hold jun back now that he has leukemia, the mother will focus on his happiness. So he might recover from leukemia and his parents will let him stay with ra-ra