You save your parents from Babili
(Questline - Map (Obtained from Greyfold, advanced by Dr.Choppy) - N-085 bunker- Any door - Go down a level - Defeat the 2 guys down there ; ask them about your parents and they'll tell you they're enslaved in Babili - Go to Babili (be prepared, there are too many ways to get enslaved there) - Head to the death arena to ask about your parents (If the option doesn't show up you may have to go to the bazaar first?) - Don't threaten the guy or you'll be enslaved instead calm down and leave - Think of another way to free your parents - Either sneak in or win a battle in the death arena - Go to the area (Nogas) where your parents said they would be after the dialogue - Ask them about the CPU and they'll give you the directions to Shine Town!)
Hope this helps!
(Ps. Being a slaver is not worth it unless you want to destroy relationships (Robin and Winston) and enslave families, it was not very doki-doki completing the questline to master rank ; Derek is freaky legit)