The ending you receive is dependent on the mystic weapons that you've collected--the axe, dagger, holy water, boomerang and stopwatch that are each hidden on stages. Collecting them all earns you the best ending while collecting only one-four gets you successively less detailed endings. In short: The bad endings are fragmented versions of the good one.
As Sonia strikes the final blow to
the Count, he falls in denial, wondering how he was defeated by a woman. They
have the following conversation:
Dracula: "Ohh, no! Me losing to a woman?"
Sonia: "You poor man. It must be difficult to understand why you, who possess eternal life, are about to perish. Humans are granted such a previous short life in comparison to yours, but in that short time we are able to love and to live for someone else. There must have been a time when you too cherished the bonds with the ones you loved. We humans are not so foolish as to throw away all of that in exchange for the power you received. There is no place in this world for the likes of you. You were already defeated when you accepted the power of darkness."
He laughs it off, comparing her naiveté to his own son, Alucard:
Dracula: "He he! HAH HAH HAH! Don't let it go to your head, girl. Do you really think that the likes of you can destroy me? You're a fool just as Alucard was. Listen to me. Darkness will never die out as long as there is light in the world. I am the ruler of that darkness and I will rise again and again, as long as people like you are alive. Again and again, I tell you. HAH HAH HAH!"
Sonia: "When that happens, someone will appear before you to take my place. If it is my fate to again be a vampire hunter, I will be ready! No, I will gladly accept that destiny. So, until your soul is saved, until all the evil desires in the world are exhaused, goodbye, ruler of evil. Good bye, o woeful Prince of Darkness."
Sonia escapes and watches from a mountain cliff as the castle crumbles to the ground. The following words scroll:
"Thus, the fear of darkness that continued to envelop the world was lifted single-handedly by a young girl. There are as many legends in the world that deserve retelling as there are stars in the night sky. But this story marks the beginning of the Belmont family legend that has been passed on through many ages. And there is not a single person now who knows when the next legendary fight between another Prince of Darkness and human will begin."
I'll leave the rest up to the images below:
But that's another legend...