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For Lydia, the best part of the day was spending the larger part of her free hours sneaking into Dr. Banner's lectures and sitting hidden in the back. She couldn't actually take his classes yet, because they required prerequisites she was still currently taking, but the courses she was taking now were boring and slow. Lydia wasn't being challenged, but they refused to let her test out of her first year classes at the college. ...which probably had more to do with the fact that she was still also enrolled in a high school class so that she could walk across the stage with her classmates in May, even though the prior May, she'd officially received her degree.
She thought she was able to blend into the crowd and remain an unseen entity soaking up every word and taking notes so that she would fit in rather than because she needed them for studying for tests she wouldn't be taking this year. From what she could tell, Dr. Banner didn't take attendance for his classes. Then again, she had missed the first couple of classes in the beginning and has, perhaps, missed some seating chart he used or sign in system she didn't know about.
All Lydia knew was that when she sat in on his class, she felt pleasantly invisible and intellectually stimulated. Those were the important things.