The comic book series Spider-man and Spider-Girl in Marvel - The New 52.
Ready to Kill
Peter Parker and May Parker begin patrolling New York City together for the first time, as both Spider-man and Spider-Girl; and father and daughter. Spider-man decides that instead of remembering his parents by honoring the anniversary of their deaths, he is instead going to honor the way they lived by celebrating their wedding anniversary. They take down a group of criminals stealing from a nuclear reactor, and May is heavily chastised for allowing their deaths. The mysterious killer Cipher murders the Spider-man of Moscow in a vat of acid, announcing that he must stop Peter Parker and his Spider Squad.
Realizing that May is a natural born killer and he must find a way to nurture it out of him, Peter worries that he might be as guilty of a parent as Calysto. They take down a shipment of arm dealers, and May shows restraint in their beatings. Peter tells her that her actions are commendable, but Aunt May chides Peter on not really being supportive as a parent. The killer slits these victim's throats when they're left for the police. Meeting Peter in person, he reveals himself to be a man named Morgan who also shares the teachings of their mentor Henry Duncan.
Peter buys May a dog, and tells her that he is proud of her self-control. He tries to forbid his daughter from leaving the apartment with Morgan still on the loose, but Spider-Girl leaves after Aunt May slips a tracer on her. When he finds the young vigilante delivering a particularly brutal beating to two muggers, Cipher encourages her darker side. Spider-man arrives to intervene, but Cipher knocks both of them out and they wake up tied to a car at a secluded drive-in movie theater.
Morgan tries to convince Spider-man that his methods are ineffective, then decides to execute him and take Spider-Girl as an apprentice when he refuses to see reason. They are rescued by Aunt May driving the Spider-Mobile using remote control. Back at the apartment, Peter reveals that Morgan is Henry's son. They argue, and May insists that she can't listen to his father if he's constantly keeping secrets from her. Taking the dog for a walk to get out, he decides to name it Ms. Lion. Once again Cipher appears, and tries to convince Spider-Girl to join him.
Spider-Girl decides to leave Peter's apartment and become Cipher's student, who insists that she still needs to prove her newfound will. Spider-man attempts to track them down, and makes a recording for his daughter to explain the history between himself and Cipher. He tells the story of how they first met, when he sought out Henry Duncan's instruction. Spider-Girl and Cipher hunt down a foreign ambassador involved with human trafficking, then Morgan puts a gun in May's hand and tells him to perform the execution.
Spider-Girl pulls the trigger, but the gun is empty. Having passes her test, Cipher takes her back to his lair where they can interrogate the ambassador. Peter continues to explain the history between Morgan and himself on tape. During their time together with Henry Duncan, Peter was an unwitting accomplice to murder and tried to leave their arrangement. Henry had Morgan attempt to murder him and tie up the loose end, leading Peter to nearly break his one rule killing Morgan in retaliation. Back in the present, Spider-Girl reveals that she had been lying to Cipher and knew there were no bullets in the gun by its weight. Despite their problems, Spider-man is still his father and he won't let a crazed sadistic murderer come between that. Morgan announces over the radio that he is going to break May and force Peter to listen to every sound.
Spider-man tears through the city streets, exploding the Spider-mobile through the wall of Cipher's hideout. They battle, and Peter delivers an even more severe beating to Morgan. Having almost killed him, he insists that they're going to leave him for the police. Cipher swears that he'll come back to kill all their friends, and tells May to make the right decision. May murders him on the spot.
Peter takes May home where Aunt May sees to both of their wounds and has them hospitalized for two weeks. Instead of getting angry, Peter tells May that he understands his problems and actually struggles with the decision of whether or not to kill everyday. His principle is that you can't build a better world by perpetuating the cycle of violence and death, you have to stand above that. May says that she doesn't want to be like Cipher, he wants to be like her father... but it's difficult. They reach an understanding, and spend the rest of the day in Aunt Mays care playing with the dog in the backyard. They play into the evening together until SHIELD calls, causing both of them to run off again while Aunt May sighs and questions if one simple night is too much to ask.