Both pairings involve a woman who is born into royalty and a man who is a criminal または outlaw.
Both couples involve a hero and a redeemed villain.
Both couples are 秒 chances at 愛 for all characters involved. Emma's first 愛 was Neal Cassidy while Killian previously loved Milah. Regina previously loved Daniel while Robin was married to Marian.
Both pairings were confirmed as True 愛 によって means other than a True 愛 Kiss. Regina was led to Robin using pixie dust, while Emma and Killian passed the Underworld's test to access the ambrosia and also reunited using a pixie flower.