This Alien Shore por C.S. Friedman? Publicado em 1998. Não consigo encontrar uma edição com a capa que você descreveu, mas os detalhes da trama são semelhantes. Aqui está uma revisão .
De uma revisão da Goodreads :
As Jamisia is trying to evade her unidentified pursuers, she also has to deal with the extra people who live in her head... If Earth finds out that she’s not normal, they will take her into custody.
Fortunately, Jamisia meets a few people who can give her some help, though they’ve got their own issues to deal with. In particular, Phoenix the hacker is trying to trace the origin of Lucifer, a computer virus that’s killing his friends when they’re hooked into the Outernet.
O cérebro de Jamisia é um protótipo.