Silently and very fast
Catherynne M. Valente2011

Neva is dreaming. But she is not alone. A mysterious machine entity called Elefsis haunts her and the members of her family, back through the generations to her great-great grandmother -- a gifted computer programmer who changed the world. Together Neva and Elefsis navigate their history and their future, an uneasy, unwilling symbiote.

But what they discover in their dreamworld might change them forever . . .