Like a couple of other prompts on here, this involves Keane waking up after he's been killed by Joe, as a new immortal. However, since the group all met Keane already, none of them dream about him, so no one knows he's now immortal.

This means, when he decides the best way to get back at Joe is to take Nicky, no one know he's the reason Nicky vanishes one day.

Weeks later, Quynh turns up. She's been dreaming about Keane, because she never met him, and she's been seeing the abuse he's putting Nicky through. She's still angry at them for not finding her, but Nicky's still her brother, and while she's happy to torture him for giving up the search for her, along with Andy and Joe, she's not willing to leave Nicky to Keane's revenge.