In an earlier posting, I examined the idea of one having a different way of presenting oneself in a language other than one's first language. This made me think of another situation in which there was a very visible change in a multilingual person's demeanor.
A friend and I took an English tour of a museum. The tour guide was Russian. Her German colleague joined her for part of the tour. As she gave the tour, the woman seemed tentative and a bit nervous. After her colleague left, the guide said that she had been losing her lovely English because she's been working extensively in German. However, she used words such as "exquisite," which is hardly a beginner's word. She was visibly shaken during the tour even though she spoke very good English.
After the tour ended I stayed to look more at some of the art. As I did that, the guide's next tour group came in and she addressed them in Russian. Everything about her changed; she stood up straight, spoke confidently, and walked briskly. The transformation was fascinating; it almost as if she was a new person!
Some of the change might be related to the guide switching to her own language after working in a second (or third...or more!) language. Also, with her colleague coming along, she might have been even more nervous. It was certainly interesting how much she changed though. It really does seem that language can shape one's expression.