Tifa: ”Two years ago… That strong feeling that he definitely had in the final battle… though it was just two years ago, somewhere along the way, he lost that feeling; I think he’s gathering that feeling again, and it’s bringing him back to us.”
During this quote we see Cloud and Kadaj continuing to go at it, but the real difference here is that Cloud is shown giving a really quick smirk in the middle of the fight. It really just reinforces everything that has happened as of late. Tifa and Vincent were able to recognize that Cloud was different and chose not to interfere for that very reason. In one last desperation attack, Kadaj leaps into the air and tries to slash Cloud, but a very strong Buster Sword meets him. At this point, Kadaj is barely hanging onto an edge; he has no weapon and is clearly beaten. But, using the contents of the box in his hand he leaps into the air and proclaims that he’ll show Cloud his “reunion.” Cloud jumps after him, but when he reaches him something is different. Kadaj now has long, flowing silver hair… a long Masamune… and in the most malicious of voices says, “It’s been a while, Cloud.” The One Winged Angel himself is back… Sephiroth was here to confront Cloud. Despite the efforts, the “reunion” of Sephiroth’s remnants was complete.
”It's been a while, Cloud.
You lost your Geostigma? How unfortunate.” — Sephiroth
”Just what are you hoping for?” — Cloud
”The spirits of the deceased who carried the Geostigma... That, with the Lifestream, guides the flow of the worlds. Eventually, it infringes on the Planet...
What I hope for, Cloud, is to use this world as a ship to sail the darkness of space. As Mother did before me, you see.
One day, we will discover a new world. We will create our shining future on that ground.” -- Sephiroth
”What will happen to this Planet?” — Cloud
”Who knows… that depends on you.” — Sephiroth
”Ooh, what made you stronger?” — Sephiroth
”I don't want to tell you.” — Cloud
”I thought of what to give you as a gift… Shall I give you despair?
Kneel, and show me your figure, begging for forgiveness.
What is most important to you, Cloud? Would you give me the happiness of stealing it from you?” — Sephiroth
”I pity you who understand nothing. There is nothing that isn't important!
Stay there for me, trapped in my memories.” — Cloud
”I… I won't become a memory.”
I feel that more than anything, the dialogue between this two in the fight does this more justice than anything else. We can see that these two still hate each other with a passion and we can see that Sephiroth is still trying to use Cloud’s supposed mental weakness—which I have more than discredited at this point—by telling him to beg for “forgiveness” and that he wants to take away that, that is more precious to Cloud. However, Cloud is beyond the point of being manipulated or told by someone else that he’s doing something that’s not right or might result in failure. Cloud knows that he cannot give up for himself and most importantly, every one else around him. He cares about his friends and those close to him more than anything. Despite not answering their calls over the past two years, he still listened to their messages and still kept his phone on him. Cloud had to sort out his own problems, overcome his “sin,” and when he finally did, Sephiroth never stood a chance. Before this fight even began, there was no way that Cloud was going to be taken down, especially by measly talk from Sephiroth. This fight, more than any other, allowed Cloud to come to terms completely with all the events in his life. He was putting Sephiroth back into his “memories” to stay there… forever.