What is "real" and what is "fiction"?
That's the basis for this story which would have qualified as "metafictional"...if the word had existed in 1951!
The writer for this never-reprinted story from Atlas' Venus Comics #14 (1951) is unknown.
Pity, since it's a clever little tale...though it would've benefited from being given a couple of additional pages to flesh out why the "creator" decided to suddenly alter the character's personality and actions so radically.
Perhaps the "creator" in the last panel (artist John Tartaglione) was, himself, being manipulated by a creator who was going insane...