Hmmm. I'd say the hints are there when the two of them realize feelings for each other but they haven't made a move yet. Or maybe she's noticed before that Deimos pays more attention to her whenever they're eating, or moving around, or working out together.

She'd be amused at first, maybe tapping her gut idly as she looks in the mirror. Then her mind imagines herself bigger and she gets flushed and embarrassed. Then shakes her head out of that train of thought.

He looks at her with less perversion and moreso admiration. And that makes her feel happy and warm. Hell at that point in their journey together, she knows he sees her for who she is, but extra little reassurances help.

Amber would absolutely tease him about it, but she'd be happy even more.