Dean's coughing put an end to Lucy's impulse to laugh. He seemed to be treading water alright, but she didn't want him choking - especially if he was one of Susan's friends. And she had to believe he was, as it seemed unlikely there was any other way he could know her name. "At least she warned one of us," she said, frowning slightly as she shook his hand. She kept behind him as he swam towards the side, ready to offer assistance if he needed it.
It took some effort for her to haul her shorter frame out of the deep end, but rock climbing meant she had more upper body strength than was necessarily obvious from her appearance and she managed it without needing help. Once she was out, she stood and pulled her t-shirt off over her head, wringing it out over the side of the pool and moving to hang it over a railing. Possibly it would be almost-dry when it came time to walk back to the house.
She turned her attention back to Dean. "Breathing any easier?" she asked. "I can go grab you some water from the house."