Characters: Blackjack and Silvala
From the story 'White Knight' which I will, eventually, write.
Silvla is Blackjack's half-sister, also affected by Shine's curse. But that is where the similarity ends. She is a disciplined Warrior of Light, trained by the Knightly Order of the Chalice.
At this point, neither has any idea they're related: Blackjack thinks Silvala is still bound by Shine (although she never was) and Silvala just thinks he's evil.