A little off-topic (and perhaps more useful for younger students) but you could do worse than introduce them to the achievements of Gauss (though they are probably somewhat familiar), who as a teenager had discovered and rediscovered several important theorems - his foundational Disquisitiones Arithmeticae was written at 21.
The books by Tent are mathematically at a 4th or 5th grade level. They’re sort of like Jean Lee Latham’s bio of Nathaniel Bowditch (you learn a fictionalized life story but you can’t really grok the person’s contribution). Of course, most mathematicians lead far more boring lives than Bowditch did in his youth, so the kind of kid who is reading Harry Potter by 4th or 5th grade is going to find them very dry.
https://www.storyofmathematics.com/19th_gauss.html
This book is aimed at a young audience, though I haven't read it and cannot say whether it is age-appropriate for late-teens.
https://www.goodreads.com/book/show/837010.The_Prince_of_Mat...