I really liked the ending, because it showed that the phantom has a heart deep down and feelings, like a normal person.

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Another ending could be...

Christine decide to choose the scorpion and marry the Phantom. And the Persian and Raoul would died in the torture chamber drowned for the water that was pouring into the chamber. The rest of the Opera and the people in it will be safe thaks to Christie. But Christine will live a life without happiness and without true love.