Once an intimate friend, Alan Campbell is one of many promising young men who has severed ties with Dorian because of Dorian’s sullied reputation. He is the former friend of Dorian Gray. Also, he is a very talented chemist and musician who was close to Dorian until their friendship comes to a bitter end as a consequence of Dorian's increasingly bad reputation. Dorian forces him to assist in the disposal of Basil's body using blackmail. But first things first. Let’s start with Alan’s character at first.
He doesn’t have a lot of lines in the book we still can understand his personality. He is very kind-hearted and calm man with a clear soul. He is a very talented musician and even scientist as you know. We see that he was a brilliant one. But nothing good can happen without Dorian. He spoiled and ruined everything Alan liked. What did he do? Well, he took this good young man, who was believed to have a perfect future and presumably corrupted him. Then, something happened and the friendship split. So, something went awfully wrong? Yes. When Dorian summons the wary Alan back, we can tell that he's tried his very hardest to put his friendship with Dorian behind him, but—you can't ever escape Dorian Gray.
At the end of their friendship, Dorian said Alan to dispose of Basil’s body. Isn’t it the awful request a friend can make? After that Alan disappears. Unfortunately, we find out that he committed suicide. To sum it up, isn’t it a lot of suicides near the Dorian Gray? Here, you may start o hate this man.
Alan Campbell in the Essays