Conversation so far:
in what way was Lord Voldemort's character developed?
Rowling said Voldemort was invented as a nemesis for Harry Potter.
what was his character like?
he was a wizard ...
did he use magic?
CANNOTANSWER.
did he ever cause any harm to Harry Potter?
Harry has to find out, before we find out.
And--so--but for some mysterious reason the curse didn't work on Harry.

Question: how did Rowling come up with the name Lord Voldemort?
Self-contained rewrite: How did Rowling come up with the name Lord Voldemort in Harry Potter?