If the "young adult" (a.k.a. Teenager) likes romances, Harlequin's "Love Inspired" lines are very good. Harlequin Presents line is also good, but there may be some PG-13 words in them. I read Harlequins since I was 15 (in the 1970s) and my mother forbade only "the ones with the red covers" (The "Desire" and "Temptation" lines) as well as any covers where one or both characters were almost out of their [ripped] clothing.
Some of the library's spicy adult historicals were in hardcover, without their dust-jackets. Actually, the values I took to heart from my parents and church made me uncomfortable with spicy and red-hot romances until I graduated high-school. I preferred Jean Plaidy's, Nora Lofts', Georgette Heyer's and Margaret Campbell Barnes' historicals and Barbara Cartland's romances (though Ms Cartland's were much of a sameness read one after the other.)
I found the novels I read for class from Grade Eight onward were more disturbing. Crime and Punishment, The Stone Angel by Margaret Laurence, Animal Farm, Who Has Seen the Wind, Fahrenheit 451, Peace Shall Destroy Many, The Adventures of Huckleberry Finn and, of course, Shakespeare's plays. Adult with a Big A adult books. Books that were supposed to make us aware of the "real world" situations, and make us think. We were directed to read the newspapers too - at least the Saturday editions if our parents didn't get the paper each day. Fahrenheit 451 turned me against "science fiction", and I never did understand all of "Crime and Punishment", but I would point them out to youth over 16 now as worthwhile reads. I think I was emotionally or mentally too young for them all at 14 and 15.
Read biographies. I read and was inspired by biographies about Florence Nightingale, Harriet Tubman, Edith Clavell, and other notable women. If you're an American, you should know about your presidents and people like Lewis and Clark, Sitting Bull, the "colored" regiment from Massachusetts who was one of the first to fight and be massacred in the U.S. Civil War. The same with people of other nations. I found it a lot easier to enter the adult world through those adults' stories than through Orwell's and Bradbury's dystopias. I've been a Sherlock Holmes fan and a Titanic "student" since age 9 and "A Night to Remember" by Walter Lord. The Titanic book was my first encounter with a tragic accident through the experiences of ordinary people, and Mr. Holmes was a genius, but not a superhero.