Luke fell to the dark side after Vader's death, and became a rival against Snoke for Big Bad Force-Wielder of the galaxy. Ben Solo eventually joined Snoke, to Luke's great disappointment.
Years later, Kylo successfully hunts Luke to Ahch-To, intending to kill him on Snoke's orders. Instead, Luke offers to become his new master and teach him the true power of the dark side.
As a sweetener, Luke offers Kylo two young Force-users he has rescued, but he believes are ill-suited to Vader's legacy. Rey and Finn are in debt to Luke and afraid to disobey him. Luke suggests Kylo do whatever he wishes with them, to see if he can finally bring them to the dark side.
Kylo/Rey/Finn, dark!Luke gives Rey and Finn to Kylo, TW: dub/noncon
Years later, Kylo successfully hunts Luke to Ahch-To, intending to kill him on Snoke's orders. Instead, Luke offers to become his new master and teach him the true power of the dark side.
As a sweetener, Luke offers Kylo two young Force-users he has rescued, but he believes are ill-suited to Vader's legacy. Rey and Finn are in debt to Luke and afraid to disobey him. Luke suggests Kylo do whatever he wishes with them, to see if he can finally bring them to the dark side.
Kylo is very tempted.