From the Dungeons & Dragons Animated Series Handbook, here are Sheila's stats:
"Sensitive and caring, Sheila would never have chosen the role of the thief for herself, and that's exactly why Dungeon Master gave it to her. He knew she would be able to responsibly use the power of the cloak of invisibility. As Bobby's older sister, Sheila feels that she has to take care of him in the Realm and provide him with a good role model. Sheila cares for her friends deeply and she fears losing them, but more than that, Sheila has it phobia of being alone. To prevent this, Sheila maintains an open and friendly attitude, hoping to win over people so they will like being with her. This can make her seem gullible, and it sometimes gets Sheila in to trouble."