Conversation so far:
In what way was Lord Voldemort's character developed?
At first, J.K. Rowling didn't flesh out Lord Voldemort's backstory. But as the series continued, she started adding more and more to his story and character.
What was Lord Voldemort's character like?
Rowling described Voldemort as a self-hating bully, a psychopath
Did Lord Voldemort use magic?
Yes, as he was a wizard, he used magic
Did Lord Voldemort ever cause any harm to Harry Potter?
Voldemort tried to kill/curse Harry Potter, but the curse didn't work. However, Harry has a lightning bolt shaped scar
How did J.K. Rowling come up with the name Lord Voldemort?
According to the author, Voldemort's name is an invented word, but it is an anagram of his birth name, Tom Marvolo Riddle

Question: did she eventually flesh out his back story?
Self-contained rewrite: Did J.K. Rowling eventually flesh out his backstory?