Jonas was the herbalist of the city of Leah and provided potions, unguents and ailments.

When Menion Leah got ill, he prepared for him several ailments to aid his breathing. Shella Leah with Jak Ohmsford came to the town and with his help they found out that Menion's illness was poisoning by dreaddire. Jonas would prepare an antidote but while the pair were looking for some missing ingredients, the royal gardener (who was Shifter, also responsible for the King's poisoning) entered the shop and killed him, stealing the book with the antidotes. The pair found Jonas's body holding a book page with the antidote recipe and thus managed to save the King.