Kathy Banner is the daughter of Bruce Banner and Betty Ross in "Past Perfect" - an illusionary world created by the Devil Hulk, where Bruce sees himself living an idyllic life with his family. (Incredible Hulk Vol 2 #27-28).
Her twin sister is Katie. Kathy closely resembles her twin, but wears bangs.
After realizing the truth, Bruce began to leave. Kathy asked him where he was going and he said he was going for a walk.