There are many pleasures to be had in watching Patti LuPone perform, particularly on a Broadway stage. There’s her powerful, flexible singing voice, undiminished at age 70. There’s her operatically expressive face, her sharply detailed characterizations. There’s also the plain fact that to see LuPone at maximum, commanding intensity — her default mode — is to see that most thrilling and increasingly rare of theatrical sights: a true diva.

(And one who has endured a diva’s share of backstage drama.) “I knew at 4 years old where I was going and what I was going to do,” said LuPone, a two-time Tony Award winner who will be starring in a revival of Stephen Sondheim’s “Company” next year. She added with a snap, “And I didn’t think I was going to be in the chorus.”