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The dragon as in, The Dragon or a normal dragon?
At any rate, you have Greater-Scope Villain, Dragon with an Agenda, The Man Behindthe Man... There are a few others but I can't recall them now.
Space Battles Dot Com fanworks (unnoficial) index in my Sandbox.
The Dragon. They created the Big Bad but isn't as strong or capable as them and even makes a Heel–Face Turn.
I thought The Dragon was supposed to be a strong enforcer for the Big Bad. If they arent strong nor an enforcer for the villains will then its NOT a Dragon.
EDIT: I didnt even read The Dragon and I still got it right! Even down to the word Enforcer! So yeah, your character isnt a Dragon sorry.
Edited by AegisP Discord: Waido X 255#1372 If you cant contact me on TV Tropes do it here.
It's an enforcer. I forgot about that, but they are.
^ That's if the annoying minion (or someone similarly innocuous) turns out to be one running everything.
Really we need more context here to figure out which of numerous closely related tropes you want. For instance:
Evil Is Not a Toy would be if they released the ancient evil, and acted as The Dragon until some line got crossed that made them turn against the Big bad
Demoted to Dragon can overlap with the previous, where a villain gets usurped by or hands over power to another Big Bad, and serves as their dragon.
Dragon with an Agenda would be if they helped put the Big Bad into power to enable their own plans, with the betrayal coming when those goals cease to align.
There's a bunch more like this, so any details could be helpful.
What do you call if the Dragon created the Big Bad?