Exes will forget you if they don’t see you

Then she picked the dead thing up and turned it around, pointing its eyes back up the street. “Keep quiet for a minute or so.”
The ex thrashed a few times against the grip, becoming more and more lethargic each time. Its arms settled down and were limp at its sides.
“Out of sight, out of mind,” whispered the titan. Her fingers opened with the faint hum of electronic motors and the Asian woman stumbled forward. Everyone stayed silent until it was halfway up the block, except for the crunch of Billie impaling another ex with her pike.

Excerpt From Ex-Heroes, pg 204
Peter Clines
https://books.apple.com/us/book/ex-heroes/id585738407