come out of your shell idiom (also bring someone out of their shell)
（使）变得不再自闭，（使）融入外部世界
If you come out of your shell, you become more interested in other people and more willing to talk and take part in social activities, and if someone brings you out of your shell, they cause you to do this.
Derek has really come out of his shell since he started working here. 自从开始在这儿工作以后，德里克真正变得活跃起来。