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

Yami-Yugi:
Kaiba, I didn't crush you on my own, Joey and I did it together, using the card he gave me. Red-Eyes is no ordinary card. Its strength comes from the bond of my friendship with Joey. That means I never duel alone, Kaiba.

Joey:
That's right.

Kaiba:
[fueling up lividly] You never duel alone?! WAKE UP! Don't you realize that every single of us is alone in this world, Yugi?! Look at me! I've never had to ask for anyone's help!

Yami-Yugi:
(thinking) That's not true. I've helped Kaiba plenty of times before and he's helped me, too! In fact, I wouldn't be the duelist I am today if he hadn't pushed me to be my best. He may be one of my toughest rivals, but I also consider him a friend. Deep down, I bet Kaiba feels the same way about me, he's just too caught up in his need for power to realize it! You don't consider anyone your friend, Kaiba?

Kaiba:
Friendship is for fools. Didn't I tell you I duel alone?! Depending on others is for the weak, Yugi. My future is in my own two hands. So keep your friendships to yourself! I'm not interested in having any pals to slow me down.

Yami-Yugi:
How sad.

Kaiba:
The time has come to accept my defeat like a man, Yugi. Since there's no one else that I rely on, there's no one else that I can blame. As per the rules, take my rarest card! [gives Yami-Yugi his Obelisk the Tormentor card]