Yu-Gi-Oh!, Season 3: Enter the Shadow Realm

Ishizu:
Marik! It's been so long since you last appeared to me. I knew that your good half took shelter within Tea's mind, but I also knew you were weak. And couldn't hold on for long.

Marik:
[speaking through Tea] That's true. As my dark side grows strong, I grow weak. But I've been in Tea's mind long enough to have learned the truth about our past. Through her ears, I listened to you tell the story of our family, and the emergence of the evil within me. I never knew that I was the one who sent Father to the Shadow Realm.

Ishizu:
Yes, but--

Marik/Tea:
I know. It was the evil force within me that committed the act, so you came here to save me from myself. Despite everything I've done in my quest for power, you've had faith. You knew there was still good within me. However, that good is almost completely extinguished now.

Ishizu:
Oh, no! If the evil force defeats the Pharaoh in the final battle, you will be gone forever, and the entire planet will suffer greatly!

Marik/Tea:
Well, I can't allow one duel to decide the fate of the whole world! The time has come for me to step in and reclaim my body, sister!

Ishizu:
But how?

Marik/Tea:
I don't know, but I must banish that evil before it's too late! There's just too much at risk.