I will reintroduce the following characters; note that ALL the characters will have explained backstories, even the villains:
Dante - has the blood of angels, demons, and humans; leader of the "Devil May Cry" special operations task force. His personality is that of DMC1 Dante with a mix of DMC3 Dante.
Eva - the angel-human hybrid; wife of Sparda
Sparda - as he is
Vergil - at first like DMC3 Vergil (the first villain); but in the end, Dante offered his help but was imprisoned by the government for his crimes. Dante comes to visit him in prison often. He served his time and now makes amends by joining the spec ops group "Devil May Cry" as Dante's adviser and master tactician and hacker (like DmC Vergil pre-Downfall). He still dislikes firearms. He is also like the Power Rangers Time Force character Eric Myers (who is also portrayed by Vergil's VA Daniel Southworth); lust for power even at the cost of his own teammates, including Dante.
Lady - reintroduced using her real name (Mary). A CIA agent (considering her VA Kari Wahlgren voiced CIA agent Sonia AKA Irene Lew from Ninja Gaiden 2/Sigma 2) but then joins Dante's group as firearms expert.
Trish - reintroduced as Beatrice (to whom Trish was named after); she will be like DMC Trish, a demon made by Mundus in Eva's image. She deceives Dante and Vergil, like Trish did to Dante in DMC1, (EDIT) but after everything, she joins Dante's group.
Lucia - a half-angel huntress who was at first assigned by the millionaire Arius to kill Dante and Vergil. Later betrayed by Arius (as he views her as a mere tool) and now vows revenge against Arius for his betrayal. In the end, she joins Dante's group.
Arius - a popular millionaire; in secret, he serves an unknown cult.
Arkham - Mary's father. A human who is the sorcerer of an unknown cult. Mary hated him for killing her mother right in front of her eyes when she was very young.
Sanctus - leader of The Holy Order (Order of the Sword reintroduced), but is also the leader of the unknown cult.
Agnus - scientist of The Holy Order, and the unknown cult.
Credo - royal knight of The Holy Order; was brainwashed by Sanctus and Arkham now serving as Sanctus' loyal servant who has no regards for his sister Kyrie.
Kyrie - reintroduces not just as a songstress but a dancer too. Her dance techniques also happen to be some battle techniques.
Nero - an individualistic member of The Holy Order, a religious order who eradicates demons. The only knight to wield guns (not just a twin-barreled revolver but a modified Uzi too). His Red Queen, like the rest of the knights, is now a more traditional broadsword. His Devil Bringer arm remains intact. He and Kyrie suspected something dark within The Holy Order and fended off the cult. He and Kyrie quit the order and joined Dante's group after knowing the order is empowered by demons.
Kat - reintroduced as Catherine (also nicknamed Cat). A human psychic who can sense the presence of demons (like Kat in DmC for seeing demons in Limbo). She was at first a normal girl making graffiti on the streets but was found by Vergil (like DmC Vergil did for Kat).when he witnessed young men (who are demons in disguise) molesting her and killed them. Cat then became part of Dante's group due to Vergil's recommendation.
Phineas - like DmC Phineas but instead is human; has wise knowledge. Dante, Vergil and the rest of "Devil May Cry" force refer him as "Professor Phineas" due to his distinct knowledge. He used to be with the cult.
Morison - a weapons dealer for the black market at first, but was apprehended and now deals arms for Devil May Cry.
Enzo Ferino - the human informant for Dante, Vergil and the rest of Devil May Cry.
Lilith - a stripper who is actually a demoness in disguise working for the cult.
Mundus - the king of demons. The demon who is worshiped by the cult. He, Argosax, Bolverk, and Sparda were inseparable friends until Sparda questioned Mundus motives and leaves his side. Bolverk went rogue as well, but still hated Sparda.
Argosax - a demon who is Mundus' heir and right hand man.
Bolverk - a demon who went rogue on his own, but hates Sparda. He sides with neither Mundus nor Sparda; he has his own motives...
Reintroduced group:
Devil May Cry - Dante's Special Forces instead of Dante's freelance gun-for-hire demon hunting business.
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And that's about it...