The group found Tifa and Cloud in the same state as when they left them. Cloud was showing no progress and things remained hopeless. They stayed for a bit, but their meeting was soon interrupted.
A Weapon attacked Mideel. Barret, Cid and Yuffie ran outside to engage it, while Tifa remained with Cloud, to keep him safe. The creature was extremely powerful, but somehow, even with Barret and Yuffie knocked out in the end, the group managed to make it retreat.
The damage was already done, however. The crust began to break apart and soon, the town was sinking into the lifestream. Tifa took Cloud on his wheelchair and tried to escape, but they failed and were gone again.
The events of Nibelheim five years ago have happened. The reactor broke down, so a Shinra team arrived with a pair of SOLDIER members protecting them. One of them was Sephiroth, but the other was not Cloud. Tifa waited for Cloud, hoping he would show up, but he never did. The other SOLDIER was a black haired man.She woke up in a world of Cloud’s own creation. He was confused, not sure what is real and what isn’t, so the world around him reflected this. Tifa decided to help him any way she can, but she was done with hiding things to protect him. He needs to face the truth.
So Cloud wasn’t there, but he definitely is real. Otherwise, how would Tifa remember their time on that starry night when they were kids, when Cloud promised to join SOLDIER and come back strong. If he isn’t real, the neither of them would have that memory.
On the other hand, Cloud doesn’t remember being that Close to Tifa. Tifa acts like they were always best friends, but this was not true. Cloud was the outsider in Nibelheim. The rest of the kids, including the group Tifa was friends with never liked him. It was only after the starry night that they grew closer for some reason.
One thing was definitely certain. Cloud was not the SOLDIER who entered Nibelheim with Sephiroth that day, and yet he remembers those events as if he was, and he is personally involved in it. Suddenly, it became clear. He was there, he just wasn’t the SOLDIER. The memories came rushing in.
The SOLDIER was Zack, the same person who went missing from Gongaga and the boyfriend Aeris mentioned. Cloud was also there, but not as a SOLDIER. He was never accepted into the ranks. The furthest he ever got was a low ranking Shinra guard. He was there, and he spoke with Sephiroth, even met Tifa, but he never spoke and never took off his mask. He was too embarrassed to do so.
When Sephiroth attacked Tifa and nearly killed Zack, Cloud came rushing after him, only to get stabbed with his Masamune. With all the strength he could muster, he used the sword piercing his body as leverage and threw it together with Sephiroth into the abyss bellow the reactor.
Cloud was fine now, so he can and will stop him. He and Tifa woke up at the ruins of Mideel, with the rest of the group there with them. They were all together again. All but Aeris…Sephiroth died that day. His body entered the lifestream and rode it all the way to the northern crater. His willpower wasn’t completely absorbed into the stream, though. He retained control and use it to influence the current events. He started the reunion, made Cloud follow his apparition and gained access to the black materia. That’s how powerful he is. That’s why he needs to be stopped.