Pochita

Unlike most Devils, Pochita communicated solely through barks and whines like an actual dog. However, after fusing with Denji, he is able to communicate telepathically with him. He continuously communicates with Denji through dreams, warning him to not 'open the door'. Pochita is even able to speak normally when he takes on a hybrid form similar to Denji's, with even Makima mistaking him for Denji. Pochita deeply cared for Denji after his life was saved by the human, despite the Devil's general hatred toward humankind. He willingly gave up his heart to Denji so that he could fulfill his dreams which Pochita loved hearing about. He also showed that he knows Denji very well and is able to mimic Denji's personality and behavior to fool Makima. By the end of the Academy Saga, Pochita willingly sacrifices his own being to create a world where he never existed to give Denji a chance to properly chase his dreams without being dragged down by constant trauma and misery. Pochita exhibits a more erratic personality when in his true Devil form, as shown when he quickly murders anyone who expressed even the slightest bit of hostility towards him in the burger joint. However, even in this state he remembers his friend Denji's wish of trying a hamburger that isn't rotten and going on a date with a girl, which leads him to kidnap Kobeni Higashiyama. Later, he tells Denji that he always dreamed of being hugged, but his strength made that impossible, implying that his murder spree at the burger joint was accidental due to him being unable to properly control his strength around others. He also seems to answer the calls of help from humans and Devils alike, proven when he saved both Makima and Kobeni from their problematic situations, though he later brutally assaulted the former after completing his task. Despite this, his love for Denji remained, as he was keen to fulfill his friend's dreams, and later even sacrificed himself to save Kobeni. In spite of being a devil, Pochita appears to have a form of attachment or respect for humanity. This can be supported by the fact he has consumed various devils that are dangerous to humanity, such as the AIDS Devil, Arnolone Syndrome Devil, Light of a Star That Breaks Children's Minds Devil, Mount Hio Eruption Devil, Nazi Devil, World War II Devil and the Sixth Sense Devil. By consuming the Nuclear Weapons Devil & partially consuming the War Devil, he also prevented any more wars from rising and the risk of nuclear armageddon. Furthermore, when Pochita disguised himself as Denji to fight Makima, he asked her whether she would eliminate bad movies from the new world she planned to create. After replying that she believes a world without bad movies would be better, Pochita realizes that he has no choice but to kill Makima, demonstrating that he does not use his erasure ability lightly and that he only uses it against devils representing very deadly concepts.

Devil Form

Being regarded as the Devil that Devils fear the most, the Chainsaw Devil is considered one of the most powerful entities in the series after the Primordial Devils and the Four Horsemen, being able to fend off hordes of Devils in Hell unscathed. The hunt for his heart alone was enough to cause an international conflict, and even Makima, one of the Four Horsemen, considered herself inferior to him, needing the public's adoration to weaken and defeat him. Per the Death Devil's plan, she empowered the Chainsaw Devil along with Yoru, as such, he exhibits a significant power boost. As a Devil, the Chainsaw Devil possesses all of the standard Devil abilities. These include the ability to make contracts with humans, restore his health by consuming blood and revival into hell after his death. However, unlike most of the Devils, certain aspects of his personality have never changed. No matter how many times he was killed, he would always come back to killing other Devils. His first contract with Denji was that, in exchange for consuming his blood, Pochita assists him to pay his debts. It is confirmed later on as a real contract rather than the "promise" presented by a young Denji. Later on, after Denji is fatally injured by the Zombie Devil, Pochita became the heart of Denji in exchange for Denji living a "normal life."