"Geth is a great king. He is wise and handsome with golden hair and an infectious laugh and and... well, he's tall"
-Clover describing Geth.
Geth has existed for hundreds of years. In Foo he was is one of the strongest and most powerful beings. He is the head token of the Council of Wonder and is the rightful heir to Foo. Eternally optimistic, Geth was outspoken against the wishes of Sabine. To silence Geth, Sabine trapped Geth's soul inside a fantrum seed and was left for the birds, but Antsel rescued him, took him to our world and planted him under the ground. Geth grew until Terry Graph (Leven's Uncle) chopped him down for destroying his house. Geth then became a toothpick who helped Leven, Winter, and Clover on their quest to stop the war of merging Reality and Foo. In 'Leven Thumps and the Whispered Secret' Geth was returned to his old self in the turrets, and The City of Geth was restored.
He is a lithen, meaning he believes Fate will decide everything. He works to keep reality and Foo from colliding against the evil Dearth who seeks to rule over both reality and Foo for the worst.
Not much is known about Geth's past, though it is mentioned he had a brother named Zale.