If your cat ate eggplant, the most likely scenario is that they will be fine. Eggplant is not toxic to cats and is actually a pretty healthy vegetable for them to eat. The main concern would be if your cat has any allergies or sensitivities to eggplant, in which case they may experience some gastrointestinal upset like vomiting or diarrhea. If this occurs, you should contact your veterinarian for advice on how to best treat your cat.