What would've been a great use for the lawyer's dragon documents would be to clearly mark incomplete/unapproved drafts, for internal review only.
Because, obviously, there was no way that you would accidentally submit a filing to the court with a huge purple cartoon dragon on every page.
Depending on the lawyer's personality, a big purple dragon might also double as lighthearted stress relief, when billing 12+ hours a day, of high-stakes work.