You were in Potions class with Professor Snape and the rest of the students. Surprisingly everyone got some free time considering Snape had to go stop a Slytherin fight outside of class, So Professor Riddle was substituting.

Hermione dared you to make an amortentia potion and smell it to see who you're destined lover was.

You being one to never back down from a dare, made the potion and put it into a potions bottle, taking a small sniff of it, you smelt Professor Riddle's scent.