The thought occurs that the “Holy Blood” and associated story details in Fire Emblem: Genealogy of the Holy War could be some great fluff for a warlock or sorcerer character in Dungeons and Dragons (at least in 5th edition, which is what I’m familiar with).
The way the minor and major bloodlines are inherited in the game would make for a great sorcerous origin, I think - ancestors made a deal with immensely powerful dragons, and took some of their blood. This blood has been passed on - sometimes weakening through generations, sometimes combining with other dragon’s bloodlines. Such ancestry can lead to abilities beyond what some would consider. . .natural...
Alternatively, the character making the pact themselves (strengthening a pre-existing bond made from lingering familial ties, or dealing with a dragon face to face) could be a rather fun way to play a warlock character.
This might seem fairly generic so far, but I think there’s a little more to it. As we see in the game, at least two of the “Holy Weapons” cause the wielders to take on more aspects of the dragons’ personality alongside their power - which I think could be a fantastic thing to roleplay! (I think such a thing could be especially interesting if the dragon in question has similar goals to your character, but different ways of thinking and acting.)
The way Lewyn was saved from death by his connection to Forseti in part 2 of the game I’ve been talking about, but at the cost of much of his original personality, is the kind of thing that is brimming with roleplay potential to me. I think it’s all the more interesting that both characters (assuming Forseti’s in the driver’s seat for much of part 2) have similar views on how it’s the common people that always suffer in war, and how you should always think critically about your own capacity to inflict evil onto others. All the more interesting because while these core morals are the same, Lewyn was rather irreverent in his actions (while caring deeply for those he loved), while Forseti is much more direct in his actions and beliefs - yet he’s downright cold to most of Lewyn’s potential children (it depends on the play-through), with only fragments of Lewyn’s original feelings showing through at times.
I think taking on more aspect’s of a patron’s character as a player levels up could be a fascinating thing to roleplay. But, hey, I’m prone to overthinking and I fear death of personality greatly - so I suppose my thoughts about this are probably unsurprising in that regard!