I don't think the youngster needs any encouragement to go into STEM. For that matter, I don't think we need to encourage any young people to go into STEM - the field is crowded enough already.
However, for those whose true passion lies in that direction, just stay out of their way.
Rather than read what somebody think is a classic, why don't you strive to get a better understanding of the medium of comics in general? For that, there is no better resource than Understanding Comics by Scott McCloud. It's not a book about comics, it is a comic about comics!
That being said, I haven't read any superhero stuff since I was 12, but in my ripe old age, I still enjoy Prince Valiant
For those that remember Calvin & Hobbes from their childhood: http://www.coffeeandcigarettes...
...and the follow up
The saddest Calvin & Hobbes comic ever (a fake I know, but still clever).
"Ninety percent of baseball is half mental." -- Yogi Berra