Ron Weasley: Traitor
I had grown up on the stories of Harry Potter so when I was told to befriend him and keep him on Dumbledore's side I was happy. I was also getting paid for it so I would be able to get myself some new stuff.
Fifth year came before Harry began to realise I had befriended him for the money that I was being paid. He began to exclude me from things that we would normally do without Hermione. After killing voldemort in what should have been our fifth year he left. I suppose it wasn't surprising after all I had left him due to my jealousy several times in the past few years, even while we were travelling to get rid of Voldemort. He sent a letter to the Daily Prophet explaining how he had felt betrayed by me and how I was not Gryffindor as no Gryffindor would do that to a friend.
I should have never agreed to be his friend for money but I was jealous of his money and to the day I regret it knowing that my actions have caused a powerful person to leave and return to a world that abused him through his childhood. Now because of what I did I will never get married or have a family as nobody want to be near someone who would betray the boy-who-lived for money. I also won't get a job as my betrayal means that nobody will trust me.