This is the battle between Gaia and Little Pete in Caine's body. This battle took place in Light. When Caine couldn't defeat Gaia using the missiles that Albert had found in a previous book. So, instead, Caine used his backup plan which was Little Pete inhabiting his body to defeat Gaia. Gaia later on, finally thinks she won the battle as she doesn't know the backup plan. Only when Caine said 'Hello Darkness', did she understand that Caine was no longer Caine and so she replied 'Nemesis'. And this was the end of the Battle of Gaia with the Gaiphage, Peter Ellison and Caine Soren dead.