Professor Pickle (ピックル教授) is the tertiary tritagonist in Sonic Unleashed. He is a human academic based at Spagonia University and a world-renowned scholar and expert in ancient literature.
When Dr. Eggman sought the power of Dark Gaia, Pickle was kidnapped and had his research stolen by Eggman due to his knowledge on the creature, but was freed by Sonic the Hedgehog, Tails and Chip. Pickle then assisted Sonic and his friends in their mission to put the earth back together after it had been shattered by Dark Gaia by guiding them to the Gaia Temples.
Not much is known about Pickle's early life. Over eighty years prior to Sonic Unleashed, Pickle met Otto and became a life-long friend of his. At some point in his life, he was inspired by Otto to embark on a research career. Eventually, Pickle became a professor in ancient literature at Spagonia University, where he would teach students in a number of classes. He also became an expert scientist on the Gaia Manuscripts and made a number of researches finding on them. He later on met Tails and came to know him quite well.
Shortly before the events of Sonic Unleashed, Pickle was kidnapped from his lab by Dr. Eggman, who sought his research and the Gaia Manuscripts to awaken Dark Gaia and use the beast's power to complete his Eggmanland project. Pickle was then carried off with his lab data by Eggman and taken to Mazuri where he was imprisoned in a holding cell in Eggman's local base.
Some time after the Earth was split apart by Dark Gaia after Eggman awoke it, Tails, Sonic the Werehog and Chip came to rescue Pickle. Though Pickle was worried and annoyed about the bad food he was being fed with during his captivity and wanted to complain to the cook, he was nevertheless freed and conviced to leave the base. Before leaving, however, Pickle got Sonic and Tails to retrieve the Gaia Manuscripts from a nearby vault, before accepting some chocolate from Chip as they left. After returning to his lab, Pickle explained to Sonic and Tails about how Dark Gaia was responsible for breaking the planet and told Sonic that he could bring the planet back together and seal away Dark Gaia by restoring the currently-drained Chaos Emeralds inside the seven Gaia Temples scattered across the globe.
From there, Professor Pickle remained in his lab to research the Gaia Manuscripts, providing Sonic, Tails and Chip with the Gaia Temples' locations in Mazuri, Spagonia, Chun-nan and Holoska, and gave them info on the planet's status. During his reseach, Pickle learned of Dark Gaia's Minions' ability to possess people, so to counter this, Pickle designed the "Uncanny Camera" to exorcise possessed people and gave it to Tails and Sonic. Shortly after, Pickle saw Sonic perform his first exorcism from a distance. After Sonic left, Pickle stepped forth and complemented his work, where he met Amy and told her everything he knew about Sonic upon her eager request.
Afterwards, Pickle continued researching the Gaia Manuscripts with aid from Amy. When Sonic and Chip returned to Pickle after restoring the fourth continent, Pickle had pinpointed the next Gaia Temple in Shamar and decided to join them there to make his analysis more efficient. Moving his lab to his research facility in Shamar, Pickle met up with Sonic and his friends where he continued researching the Gaia Manuscripts and located the Gaia Temples in Adabat and Eggmanland.
When Sonic and Chip were restoring the last continent, Pickle reported to Tails over his Miles Electric about the restoration process until he was interrupted by an attack on Tails' Tornado-1. When Perfect Dark Gaia then began casting the world into darkness, Pickle and Amy got outside to see the darkning sky, where Pickle gave into despair as the world seemed doomed despite Amy's assuring him Sonic would save them. However, Super Sonic and the Gaia Colossus defeated and sealed Perfect Dark Gaia away, which Pickle praised as a miracle as the world returned to normal. As Pickle then admitted to Amy that she was right, he reflected on how Light Gaia and Dark Gaia were a part of the planet's desire for balance when he was dragged with Amy to prepare for Sonic's coming-home party.