In The Deep by Pache

In The Deep Manhwa Plot: It’s been years since Haemin first began craving blood…and only his brother’s will do. Something uncontrollable has called out to Haemin since he was a young boy: an animalistic urge that won’t quell until he’s had his share of blood. Despite this, his younger brother Dogun will do whatever is necessary to keep him safe…and that includes lending him a hand (or vein) whenever his thirst takes over. On top of this, as an elite agent, Dogun needs to fight off the mutants that have begun to invade the world. As the two brothers try to survive in a world full of ravenous beasts and calculating figures disguised in shadows, they uncover secrets that were meant to stay hidden far below the surface.