I always of course like to think about authors, since I want to be a writer...
Shakespeare at 20...who could've ever thought he'd become who he became?
20 years old, that'd be 1684 or so for him...he wouldn't have written any of his plays yet, and wouldn't write them for years to come yet...he probably was still a few years away from writing his sonnets...probably was little more than just an apprentice in a trade like a father, or already an apprenticed actor...
I wish history could allow us to know what he was like then!
T.S. Eliot didn't change all that much, I suppose...he was already writing poems, and already writing in his time at first Harvard and then Oxford, and most don't describe him changing all that much, still the same coolly intellectual T.S. Eliot...
F. Scott Fitzgerald didn't change much either, but from the opposite end--writing, boozing, partying, and getting into trouble in college at 20, and that was...well, pretty much his life, until the tragedies of his later years.
John Keats...THAT is someone I'd love to have met at 20, though!
His poems got scathing reviews then!
And then...he met Fanny Brawne a little later...
And POOF! Suddenly he had his muse, and his poems tick right up in quality it seems...
How fun would it have been to meet him at 20, when you could've known him just before and just after that meeting...he died at 25, so that was the great change in his life--imagine meeting him before and after, what must he have been like before to produce poetry that was well-worded yet lacking in soul, and right after, when he became the practical embodiment of the modern-day artist/rock-star:
Live young, die young, drink, sex, under-appreciated in his own day, a relationship that never quite works out, die young, and instantly he's a sensation overnight, the instant he dies...he's like the poet/singer stereotype personified! xD
(As for me at 20...well, you all were there for it, I'm older than that now, obviously, but you all were there...so who knows--if I ever make it in writing, you can all release these embarrassing transcripts or all ghostwrite a book--maybe collectively sign it "The Ghostmaker?"--and expose me for the ponderous schmuck I am on here!) ;)