I’m pretty sure Rumple will be the person who Merlin predicted would eventually be able to wield great power without giving into the darkness. Hence, Belle will be able to live with his status as the dark one, provided he only uses his power for good, rather than for evil. With all that being said, however, when I actually pause to consider it, I don’t see how Rumple will be able to prevent the darkness from consuming him. His heart actually turned coal black the last time. What makes him think he’s suddenly capable of not letting the darkness consume him again? What’s to keep the darkness at bay this time–just because he has all the combined power of previous dark ones now? I’d expect that to amplify the darkness, not decrease it. *head desk*
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy