Remus was the smart one. The prefect. He always knew what to say, what to do. In control. It made sense; he lost his humanity once a month, so he otherwise tried to control what he could.
James was impulsive, rash. He did what he wanted, regardless of the consequences… until he met Lily. Then he tried to be mature and composed, trying to impress her.
Peter was the sneaky one. Good at getting himself out of tight spots. Good at finding hidden information, at spying. Look how that turned out.
And Sirius… he was lost. He was scared and afraid and… lost. Azkaban can do that to a person.