What I think most people are missing when Ayn Rand writes about Hank and Dagny is that they’re the last two standing. They’re both driven to success and define their lives by their success.
As two people with very powerful personalities, of course they are drawn to one another. There is no one else they know that is as they are.
At this point, both Hank and Dagny are not only sharing their passion, they’re also using each other to try and insulate and reassure themselves against the coming collapse. A collapse they see happening all around them, yet deny there is nothing they can do about it.
Excellent point. Such passion is rare among the sane.