The Dog. The Wizard.

1993, 130 years after Ciel Phantomhive has become demon, the current queen is worried about a certain student at a certain witchcraft and wizardry school and thus, as a final resort, contacts a family she has heard of that could help her situation. Ciel infiltrates the school as a first year student as Harry starts his 3rd year. (The Prisoner of Azkaban)