But what if Rhaegar hadn't raped Lyanna and they had been in love? The seed of that possibility comes up when, in the same episode, Ser Barristan recounts a sweet story to Daenerys about her brother going out into the city to sing to the people. "Rhaegar never liked killing; he loved singing," Barristan says, essentially making the claim that Rhaegar was actually a good and gallant man. This is Daenerys and Barristan's last conversation, so his anecdote means something. I think it's supposed to establish Rhaegar as an honorable person, not a villain, as only the father of someone like Jon could be.
Of course, in season seven, it's confirmed that Rhaegar was good — or at least, he's not an adulterer. He and Lyanna were in love and their marriage was legitimate.
