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While her commander opened the door into unchartered territory for her, she listened for his reaction, knowing he would see whatever was inside first. In the meantime, her attention swept the wide hall behind them, not wanting to give up her guard prematurely.
He wasn't wasting any time, it seemed (though caution was never wasted time to her), and she followed him in, almost back-to-back with him. Trusting his reaction in place of her own, she didn't turn around until the door was shut in their wake.