Nora is a serial becomer. She has become many things in her life, though rarely on purpose. The first time, it just sort of happened. The second time, it was a coincidence. Now, it is a habit she cannot seem to break. In the past, she has become a rock climber and a scuba diver, a beekeeper and a gardener and a mechanic specializing in European cars. For two months last summer, she was a stand-up comedian. Her senior year of college, she amassed New England’s largest collection of antique coins.