Are you ready? This is important, so listen to me carefully, Shinji-kun. It's been 14 years since the fight against the Tenth Angel. You and Unit-01 triggered Near Third Impact, which was contained when Eva Mark.06 pierced Unit-01's core with the Lance, but it was still a disaster that wiped out most of humanity. Afterwards, you remained sealed inside Eva-01, which was now orbiting Earth. We rescued you, but Ayanami Rei was nowhere to be found. You were unable to save Rei.
We've formed an anti-Nerv organization called Wille, with the aim of annihilating all of Nerv's Evas. We're using Unit-01 as the main engine for our flying battleship, the AAA Wunder. From now on, if you awaken an Eva in the future, the DSS choker we put around your neck will activate and kill you. This is insurance to give our crew peace of mind. I'm sorry.
Also, I don't know why, but you and Asuka seem to be under some kind of Eva-related curse, resulting in you both looking the same as you did 14 years ago, even though you're both 28 years old. This doesn't mean you can drink alcohol. You're treated as a dangerous person here on the ship, for causing Third Impact. Don't get any ideas.
Anyway, there's a person at Nerv who looks like Rei, but she's not the same person you knew. Don't let them persuade you to join. And don't let Seele's homo aim for your ass.