Creation and Traveling to Path
When Andrew Wiggin traveled to the Outside along with Miro and Ela Ribeira, he created two genetically identical clones of his brother and sister, Peter Wiggin and Valentine Wiggin. Peter II and Valentine II shared an Aiúa with Andrew.
Jane, using her faster-than-light travel abilities, took Peter to the world of Path to deliver the cure to the OCD-like symptoms of the Godspoken to Han Fei-tzu. There, he met Si Wang-mu, and he asked if she would like to go with him to overthrow Starways Congress. At first she was unsure, but Han Fei-tzu convinced her to go with Peter and leave her home behind.
The two adopted the singular mission of convincing Starways Congress to halt their attack on Lusitania. To do this, they embarked on a series of investigations and debates to pull an influential swing vote to their favor. Peter believed that the center of power in Congress was not held in the hands of politicians and soldiers, but rather several key philosophical leaders who had the tendency to influence policy. To this effect, Wang-mu posed as an itinerant philosopher specializing in cryptic "gnomic" sayings--presumably a position of great influence for someone of her age. Peter posed as a traveling physicist so that the two, working together, would draw more attention to their combined arguments representing both science and philosophy, respectively.
They first traveled to the planet of Divine Wind to probe the questions of imperialism with Aimaina Hikari. When Peter failed to connect with the withdrawn social figure, due mainly to a lack of cultural context, Wang-mu engaged him in a duel of humility to win his respect. While the two failed to persuade him to their cause, they in turn found out that he was a disciple of a Samoan holy man: Malu. Jane revealed that this was actually their mission all along, as Malu was the guiding light of modern philosophy. Since Aimaina contacted Grace Drinker first, the two traveled to the planet Pacifica in an effort to contact him through her.
Once they arrived, it was immediately apparent to both Grace and her family that Peter and Wang-mu had achieved the impossible and traveled faster than light. After a series of additional cultural blunders, Grace revealed that the two were not holy enough to go see Malu, but that in a compromise, Malu had decided to see them.
A New Beginning
After listening to Malu at length, Andrew Wiggin began dying on Lusitania, causing the extensions of his Aiúa, Peter and Valentine II, to fluctuate. As Peter started to fade into death on Pacifica, he underwent an intense personal transformation, and Wang-mu began to realize that a deeper connection had formed between the two. As Peter slipped in and out of alternating states of death and waking, she became an emotional--and more importantly, spiritual--anchor for him that allowed him to draw the complete life source out of the dying Andrew. Having taken full possession of the life force that was once divided in three bodies, the fully reborn Peter lost much of his acerbic nature, and the depth of his feelings for Wang-mu were now open and shared. The two forged a metaphysical bond during the process that caused the two to fall deeply in love.
Once Peter was made whole by being in full possession of Andrew's Aiúa, the pair traveled directly to the Lusitania Fleet to confront Admiral Bobby Lands. Though Lands had already launched the Molecular Disruption Device, Peter convinced Jane to transport it back to the flagship so the other officers could disarm it. Once Peter and Si Wang-mu delivered a series of messages for Starways Congress, they transported themselves back to Lusitania.
He eventually married Wang-mu at the roots of a Pequenino Mothertree in a dual ceremony with Miro Ribeira and Jane shortly after Andrew's funeral and speaking by Plikt. Having earlier expressed a desire to travel to the known colonized planets, the four disappeared as Jane transported them away for their travels.
Like his predecessor, Peter II was known to be cynical and rude, often lashing out at the others around him. As he progressed through his travels and learned to interact with people better, he softened his attitude and became less harsh. When he obtained full possession of Andrew Wiggin's Aiúa, Peter became more like him.
- The title of the book Children of the Mind most likely refers to Peter II and Valentine II, coming into existence fully formed like Athena springing from Zeus's head - a child of the mind.