Encountered: Chapter Nine - near the fountain on Willow.

When Aislinn meets Donia near the fountain a block from her house, several young kelpies play nearby:

'"When you're ready..." He looked like he'd rather stay beside Aislinn, but she motioned him off - watching as he passed the fountain.
Inside it young kelpies were playing. Like most of the water fey, they cared little for the other faeries in the park. They were still disquieting to Donia in a way that most of the fey no longer were, preying on mortals when given the slightest chance, drinking down their last breaths, somehow making death a sexual thing. Not even Irial's Dark Court disturbed her the way the water fey did.
Of course, Seth - like most mortals - didn't glance at them, but as he passed they stilled, watching him with that eerie hunger they had. They could see the passion in him, feel it somehow, or they wouldn't watch him so.
[...]
Beside her, Aislinn shuddered. She stared at the fountain, or perhaps past it where her mortal stood. "I guess it freaked me out a little. Seems unreal, you know? And the sort of things that come out at night..."
Donia sat up. "Things?"
It was an odd word to choose, an odd tone in her voice as Aislinn stared towards the kelpies.' (pg101 and pg102)