@Fried pancake it stated in earlier chapters that they glow red under torch light, he believes the reason is due to the white snake in the room he was in. Although I'm not too sure, i believe it has something to do with the unusual eyes the snake had. And how he kept staring into them and letting the snake bite him
Spoiler!
I want an action packed manhwa like My S-class hunters,lout of the count's family, Solo leveling, but it has a Bl tag
Never mind I found one-