The Butler, Relentless is Chapter 161 of the Kuroshitsuji manga.
Meanwhile, at Phantomhive Manor, Ciel asks Sebastian what has just happened. Sebastian informs him that a sniper tried to kill him from such a large distance away from the manor that Sebastian neither sensed them nor heard the sound of the rifle cock. Still, the sniper was able to accurately aim for Ciel's head. Then, Sebastian opens the bedroom window and tells Finnian who is standing below that he does not need to chase the assailant and has to stay and protect Ciel instead.
Sebastian quickly washes and clothes Ciel and serves him his breakfast before he excuses himself to chase down Mey-Rin himself.
Far away from the manor, Mey-Rin is hiding behind a bush when she sees someone running into her direction at an insane speed. She takes a closer look at the runner and recognises Sebastian. Immediately, Mey-Rin prepares to shoot him, but Sebastian dodges all her bullets and closes the space between her and him. He takes out his silverware, and Mey-Rin believes for a moment that he intends to attack her—until Sebastian throws a knife at Dove who was sent to silence Mey-Rin. Dove dies, and Sebastian disarms Mey-Rin and takes her with him.
Back at Phantomhive Manor, Sebastian presents Mey-Rin and her rifle to Ciel and points out that there is no sight for long-distance shots on the weapon. Ciel recalls the intelligence he has been given: that Haku from Qing Bang wants to murder him and that one of Haku's underlings is a talented sniper called "Owl."
Mey-Rin is shocked that he knows this and wonders if he has a spy in Qing Bang. She tells Sebastian to kill her quickly, not to torture her. Sebastian replies that he will not torture her as he believes torture to be inefficient. Then, he offers her his hand and asks her whether she would like to work for the Phantomhive family—surprising both Mey-Rin and Ciel.
Ciel protests as Mey-Rin tried to assassinate him only a few hours ago, but Sebastian reminds him that he barely has any servants and desperately needs more because Finnian cannot handle assailants on his own. Furthermore, Mey-Rin is an excellent markswoman and, thus, perfect to guard Ciel and the manor. She also has no place to which she could return as Qing Bang will execute her the second they catch her. Therefore, Sebastian's proposed arrangement would not only benefit Ciel but Mey-Rin too.
Lastly, Sebastian reminds Ciel that he once expressed his wish to hire a maid and reveals to him that Mey-Rin is a woman, surprising Ciel once more.