Ending her misery!

Ciel was very upset about what Isiah did to Lexie, and for the next half an hour he didn't even talk to him, while Isiah was just looking at the small body of that girl as it was laying on the bureau.

At first, he really regretted the fact that he didn't kill her , however, as he kept looking at her he realized that she was crying during that time.

The fact that she didn't resist while he was strangling her was one of the reasons that made him more curious about her, the taste of revenge was never going to be good if the person he was killing didn't beg for his life.

Because at this point he was just going to do her a favor by killing her and ending her misery .

Ciel got closer to her and started to wake her up with tears in his eyes, which made Isiah very uncomfortable, Ciel was always having that sad smile on his face because of the dark past that he never shared with him, however, seeing him cry made him think that he is indeed a monster.