Dr. Jekyll and Mr. Hyde is definitely not a story that has been done well recently. And this Once Upon a Time version is not a very good one either.
We first see Dr. Jekyll alive and we see his backstory. He seems to be a good guy on the side of the heroes.
But then we see him one day try to hurt Belle as he wanted revenge on The Dark One.
At the end of his story he is killed by Killian Jones who shows up at the last minute to save Belle.