It's not that this is a pairing. It's Ragna's weapon that Ruby is interested in.



Ragna: Leave me be, I have someone to bring to justice.



Ruby: Who the hell are you going after?



Ragna: The Branwen Family, they framed me and the law put a price on my head very large. I'm going to take every single Branwen alive and bring them to justice to prove I'm innocent.



Ruby: You can't!



Ragna: Why?!



Ruby: Branwen blood is too powerful, they could kill you in one blow.



Yeah. Ruby warned Ragna that he can't defeat the Branwen family despite they are evil murderers and bandits and unchecked unchallenged killing at will, and she give him a paper with a symbol that is a heart set on fire saying "This is why."



I've seen that symbol a lot so what the hell is that burning heart symbol and why is that symbol is around. Tell me, what the hell is that symbol?