Having been a mere year older than he, Minerva McGonagall was enrolled at Hogwarts at the same time Tom Riddle was, but rarely did anyone ask her about him. Perhaps nobody cared about Voldemort's school years when he went by Tom and his features were handsomely chiseled. When his keen interest in his family tree morphed into obsessions, and when his obsessions took a back seat to his hormones. She knew it all too well; she was acutely aware of the gossip surrounding him–and all other cute Hogwarts boys, for that matter–being the teenaged girl she was, her hormones raging no slower than those of Mr Riddle. Students of hers would scoff now, but Minerva, too, was once like them. So she wondered why people never asked. She wondered if she would tell them the truth if they were to inquire. Perhaps she shouldn't trust her memory, it was so long ago.
Perhaps she didn't want to trust her memory.
When Minerva McGonagall was a seventh-year, she toiled over her studies. Some of her girlfriends took their impending freedom as one-way tickets to nights of drunken debauchery and countless more run-ins with older boys, but not she. Minerva took her studies excruciatingly seriously, because she wanted to do big things. She wanted to discover new spells and save lives and change the world. She envisioned being a researcher, an auror, even a teacher. She was not unlike her future ambitious students. She had a world of opportunity placed neatly in the palms of her hands, and she wouldn't give it all up for a night of boozing and sex not necessarily to be remembered the next morning. By no means was she a prude; she just had her priorities straight. School came first.
Truth was, she didn't really know too much about Tom Riddle–perhaps she'd heard of his charm and good looks–but he seemed to know that about her. In retrospect, she would not seem to determine whether it was a power move. She was fulfilling her Head Girl duties when he cornered her in the library and engaged her in conversation. She'd like to think that something about it was particularly chilling–perhaps that it warned a certain foreboding–but she knew that was never the case. Tom Riddle had a reputation for being a charmer, and that he was. He seemed to know all the right buttons to push, and was cold, yes, but only comfortably so. She believed he understood her pursuits, beliefs, and plight. When he smiled in that distorted, distant way of his, she succumbed to his charm and charisma.
He kissed her behind the book stacks that day, and she let him. She let him hold her, run his fingers through her hair and brush his lips against hers, and she kissed him back, waves of excitement rippling through her body as he kissed her neck, her shoulders, her neck again, each time with a sensual delicacy.
She never blamed herself; she was young and naive and it happened only once. But sometimes she wonders what she would say if someone asked her about Lord Voldemort's early years at school, when he was just Tom, and not "He-Who-Must-Not-Be-Named."