What happens at the end of persona 3?

Answer 1

At the end of Persona 3, on the final day, the party ascend to the very roof of Tartarus. On the way they battle Jin and Takaya for a second time, defeating both. On the roof, they face the Nyx Avatar, the fused form of the defeated 12 major shadows and Pharos/Ryuji, the fragment that was sealed inside the protagonist.

This avatar cycles through 13 arcana in total, changing its strengths and weaknesses, as well as attack patterns. Once it reaches the final arcana, Death, it can be defeated. However it announces that it in itself does not bring The Fall, it is merely a herald of the being who does. So saying, the moon itself reveals itself to be the true bringer, Nyx.

Nyx crushes the team with its immense power, but the bonds that the protagonist has made empower him to stand. He rises up to face Nyx's true form, a golden egg with limbs made from spider's webs. He is struck down, but after briefly visiting the Velvet Room, awakens a new power, the card of the Universe. Since Nyx cannot be killed, he uses his new powers to seal it away.

A few months later, the team are getting ready to graduate. Now the Dark Hour and Tartarus have gone, they have forgotten many of the events of the game, including their own relationship with each other. Only Aigis remembers, as she is a machine. However as Mitsuru gives her speech, they all suddenly remember, and reunite on the school roof. The protagonist though has been feeling tired all the time - the game ends with him falling asleep on the roof with his friends. The follow-on game reveals that the protagonist died here and left his 'wild card' power to Aigis. His life force became a seal, blocking a malevolent being called Erebus from calling Nyx.