At its core, Return of the Jedi is a family drama on an epic scale. They don't call the Star Wars saga a space opera for nothing.
Luke and Anakin, a.k.a., Darth Vader, have father-son problems the size of Tatooine. Vader, meanwhile, has his own daddy issues with The Emperor; all he wants is his approval. Luke and Leia's brother-sister bond is equally knotty; for starters, there's the fact that they were raised separately, not knowing the other one even existed until they were adults.
In short, when it comes to the Skywalker clan, relationships are complicated, and mending their broken family bond is the galaxy's only chance for survival.
Questions About Family
Why were Luke and Leia separated at birth?
Does Luke have a right to be mad about everybody lying to him about his family tree?
If Leia knew deep down that Luke was her brother, how come she never said anything?
Why does Darth Vader ultimately save Luke from The Emperor? And, while we're at it, what takes him so long? We mean, he lets The Emperor zap Luke with Force Lightning for a long time before he finally puts the kibosh on it.
Chew on This
Luke's refusal to go down the same malevolent path as his father proves that nurture is stronger than nature.
Darth Vader and The Emperor have a thoroughly dysfunctional father-son relationship.