Mary worked as part of the crew on the Project SEEDS ship, a deep space colonization mission. She and Rem were on good terms—they're shown hanging out together with Vash and Knives over lunch at one point.
Two of her crewmates, Steve and Rolan, both had romantic interest in her. Mary didn't seem to return their feelings, though she did muse to herself that things would be pretty dull if only one of them liked her. Fans often note the dynamic creates an amusing contrast to the more serious elements of the series.
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