The Purple Dragon (Dungeons & Dragons) is a type of dragon in the Dungeons & Dragons universe. It is an evil-aligned chromatic dragon.
Purple dragons, often confused with deep dragons, are possibly the least well known of the chromatic dragon family. Most surface creatures have no knowledge of the existence of purple dragons. Many of those that have heard of purple dragons dismiss such stories as myth or misconception. After all, in the darkness below the earth, who can say whether a dragon’s scales are purple or black?
Black dragons rarely live far underground. The deeper explorers descend, the more likely they are to encounter a purple dragon than a black. People who live permanently in the deep hollows of the earth know purple dragons as an all-too-real and a much feared threat.
A purple dragon is a talented manipulator of other creatures. It achieves control through lies, misdirection, and direct mental domination. A purple dragon might seek control for any number of reasons, including sheer delight in bandying its power about, a desire to form a bulwark of allies and thralls for security, or curiosity about newly discovered tunnels or crevices leading to unknown areas deeper below, for which recruiting bands of disposable explorers might serve its purposes.
I’ve got some serious doubts about the character of anyone who presents themselves as a purple dragon.
https://dragons.fandom.com/wiki/Purple_Dragon_(Dungeons_%26_Dragons)