Sloth: Peter Pettigrew
If anyone asked Mrs Pettigrew which of her children was the hardest working and enterprising, she wouldn't answer "Peter". Peter, by his mother, had many qualities; brave, generous, loyal, everything a mother could've ask for; except pro-activity.
Since Peter was a little boy he was chubby and not that active, more preoccupied of waking up late and eat candies, than to run around the backyard and chase his older brothers.
The little Pettigrew was quite bright, he understood perfectly the things that were explained to him, but he wasn't applied in school. He wasn't an erudite in the facts of life; however he always had a minimum amount of knowledge to pass unnoticed; and he didn't reach for knowledge outside his reach.
The day Peter got his letter to Hogwarts he could only think about how miserable his life would be without the pampers of his parents; even so he would make them proud.
By the third day of class Peter was a Gryffindor, siting by the first friend hemade on the train; Remus Lupin; and realizing that if he stayed close to him his life would be easier.
By third year he discovered that Lupin wasn't what he seemed, and that his secret would make Peter's life harder and not easier. However his other two roommates were whiling to make Lupin's life more confortable, and if he wanted to continue his life without so many troubles he had to join their plans.
It was true that not everything was relaxing and chilling, but the subjects; thanks to the notes of his friends; weren't as hard as they seemed, and he didn't have to spend so much time amongst thanks to the "extracurricular" activities.
By fifth year his new form allowed him to ditch everyone and sleep inside the cracks of the castle, while the rest spend their time reading in the library.
Peter's life was entertaining and safe, he was an Animagus, sixth year Hogwarts' student, he had a basic goal for a simple work in the Ministry, and everything was according to plan. But Peter wasn't counting on the war. The war day by day ate away the magic society and threatened Peter's future.
Peter's life made a turn at the beginning of the seventh year, the almighty war that had left him alone all this time arrived to his home. His father was murdered for marrying a Muggle. This made Peter reconsider some stuff of the first time in a long time.
Would the same that happen to his father, would happen to Peter? Would his mother be safe? Could he get a decent job after that incident? If things got to the point where his father, a man that did no harm to anyone, was murdered; what was left for Peter?
When Peter graduated from Hogwarts he arrived at the Minister, his friends had other destinies but they manage to catch up every couple of weeks. Things for Peter were going down hill, he didn't have the fortune of the Blacks or the Potters, and things with Remus weren't that great. That's why when Malfoy offered him a change at his 19, Peter didn't doubt to take it. He just had to make some questions and inform him of the answers, what's that too much to ask for his safety?