Best Devil-Human Friendship

Pochita was saved by Denji when in his time of need by feeding him his blood to recover from an injury, leading to them befriending one another Devil and Human alike. This allowed the debt that filled young Denji to be dealt with by becoming a young Devil Hunter with the help of Pochita. Later after being a Devil Hunter his whole life Denji was betrayed by the debt collector and brutally murdered by zombified humans. This death caused Pochita to become Denji’s heart due to a contract making Denji a Devil-human Hybrid. https://chainsaw-man.fandom.com/wiki/Denji