Character:Su Tan

Su Tan was an alchemist in ancient China - before "China" was even a nation with borders - who learned of several medical treatments by experimenting with ways to extend human lifespans. Unfortunately, he died after accidentally creating Hydrogen Sulfide, which quickly became a gas and suffocated him.

Post-Resurrection
After being told that at some point in the distant future, mankind had achieved immortality for all, Su was immediately intrigued and became a full-time chemist. Although he made a few lethal mistakes in the process, he was able to make great advances in chemistry without having to worry about permanently dying from his craft.