Looking for BL manwha

Every since the list purge, I've been trying to find certain titles again. There was one I really liked thst Google hasn't been able to find.

It followed two characters: a blondes male that can shift into a gold dragon, who is masquerading as his dead twin and is some sort of guard captain. the other a black-haired male with seals on his tongue and stomach from childhood experiments.

Thanks