A round character has a complex, multi-layered personality, which reflects the emotional depth of a real person. Round characters are also physically and mentally fully developed and capture the audience's sympathy. In contrast, a flat character lacks emotional depth and remains the same throughout a story. Flat characters are undeveloped and do not undergo a significant transformation. The role of a flat character is to support the main character, and they tend to have recognizable, stereotypical traits. In regards to S. E. Hinton's classic novel The Outsiders, Dallas Winston is definitely considered a round character.
Dally is a round character because he is fully developed, shows emotional depth, and has a complex personality. The audience can sympathize with him. Hinton portrays Dally's emotional depth by depicting him as a rough, callous individual who has a soft spot for Johnny and is willing to risk everything to help his friends. Although Dally is a ruthless criminal, he is also a loyal friend who earns Johnny and Pony's respect. Dally is also a product of his environment, and his cold demeanor allows him to survive on the unforgiving streets. Despite his rough exterior, Dally has a sensitive heart and truly cares about his friends. He not only helps Pony and Johnny skip town but also saves Johnny's life during the church fire. Johnny praises Dally for being valiant, and Pony also develops a reverence for him. The audience sympathizes with Dally, and his suicide is a tragic moment in the story.