Why Does Vermouth Never Age?

Vermouth's appearance 20 years before the current timeline. For some reason, Vermouth does not appear to age. Her apparent age hasn't changed since she murdered Jodie's parents twenty years ago. Shuichi Akai proved that Vermouth was not wearing a mask when his shotgun fire grazed her face.

Why does Vermouth protect Conan?

Why does Vermouth always try to protect Shinichi and Ran??

When Gin asked her about Shinichi, she denied knowing him although she knows very well Shinichi's identity. And when someone try to hurt Ran, she will do everything to protect her, she even sacrificed her cowoker_Calvados, just to keep Ran's life.

How did Vermouth know Conan is Shinichi?

Vermouth. Vermouth realized similarities between Shinichi (when he was young) and Conan. She also chose not to betray Shinichi to the Black Organization, most likely because he and Ran saved her when she was disguised as a serial killer in New York.