Oh, a form of communication that dealt with phones. Charlene had played with one of those once on a street corner. She could see how people who spoke could get a use out of them, but it seemed pointless to her since she could not. But just the phrase 'text messaging' seemed to convey a different use... perhaps they sent messages? She smiled and shook her head at the idea of a mother worrying over her grown child; her own had not batted an eyelash when Charlene had informed her that she was leaving the pod. But then, a lot of things were different outside of her pod. And if Roxy's mom was anything like her then it would explain quite a bit.
Charlene's face fell a little when Roxy said that she had to leave - a small voice somewhere in her mind demanded to know if she had taken leave of her senses - but her mood lifted considerably at the question. She let out a series of excited trills in response before another word quite literally forced itself out, embarrassment at how odd she sounded pushed aside, "Yes." The fact that Roxy was not put off by her being a mermaid or having sang to her - a pang of something, Charlene did not know what, tugged at her remembering that - or kissed her made her skin tingle. The fact that Roxy had not run off screaming could have been an indication, but wanting to see her again was much better.
Knowing that it would be too dark to write, she reached up to trace out her question on the nearest bit of Roxy's skin she could reach with the pad of her finger, making sure each letter was clear, with a long enough pause between each to not make them blend together: Coffee; where & when? She had had coffee a few times while at markets selling some things and it always gave her a pleasant burst of energy, even if it was followed by being strangely tired awhile after.