We find that in Oscar Wilde's The Picture of Dorian Gray the author intends to present to us with a character whose presence causes a number of extraordinary reactions in those who meet him.
Dorian Gray, a dandy, is a man of unique personal beauty who seems to cast a spell on every person he knows. This is, in part, because he is hiding a big sin: He sold his soul by wishing that his picture would grow old instead of him. When his wish is granted (Wilde does not attribute this odd miracle to anything in particular) the picture not only begins to age (while Dorian remains young), but Dorian himself becomes a creature of evil, looking good as always in the outside, but committing horrid things in the underbelly of London.
This being said, what Wilde intends to do with Dorian is to attribute him the power of both creation and destruction, all caused by his immense beauty. This is Wilde's own reflection on his adoration for physical attractiveness in men, as a classic, Greek ideal.
Basil Hallward is the person most affected by Dorian Gray. It is through Basil's fascination with Dorian that we get to understand Wilde's purpose. Here is an example of when Basil met Dorian:
I turned half-way round, and saw Dorian Gray for the first time. When our eyes met, I felt that I was growing pale. A curious sensation of terror came over me. I knew that I had come face to face with some one whose mere personality was so fascinating that, if I allowed it to do so, it would absorb my whole nature, my whole soul, my very art itself. I did not want any external influence in my life. You know yourself, Harry, how independent I am by nature. I have always been my own master; had at least always been so, till I met Dorian Gray.
Hence, Dorian Gray's description is meant to cause both attraction and rejection, fear and curiosity. Above all, he is to be characterized as temptation itself would be: Lovely to the sight, but bad for the soul.
Then—But I don't know how to explain it to you. Something seemed to tell me that I was on the verge of a terrible crisis in my life. I had a strange feeling that Fate had in store for me exquisite joys and exquisite sorrows. I grew afraid, and turned to quit the room. It was not conscience that made me do so: it was a sort of cowardice. I take no credit to myself for trying to escape.”
If you notice, the character of Dorian exhibits all the elements of sin: Temptation, Action, Emotion, Destruction. That is what ultimately he really represents.