Wei Zi Riding Animation

Black deacon? Ciel phantomhive (シェルファントムハィヴ) usually wears an eye patch on his right eye. See figure

Shiru Panduomu Haiwu

French original: Ciel? Phantom hive

Another translation: Shel Van Dom Heywood? Sial Fadom Haibei (Comics)

The right eye with blindfold (purple pupil) is marked the same as Sebastian (deed). ?

This "contract mark" has the ability to order Sebastian to do anything for Charles, and it must be absolutely obeyed.

There is another explanation for this "contract mark": the devil must help his master do anything and swear to protect his life before helping him fulfill his wish.

The contract mark is also the mark that the devil uses to track the person who makes the contract, which means that the person who makes the contract must never escape from the devil. After the contract is completed, Charles' soul will belong to Sebastian. (Quote Baidu Encyclopedia)