Nerien appears to warn the Dragonborn that their actions in Saarthal will trigger a chain of events that cannot be stopped, and that judgement will be passed on their actions to come and how they deal with the dangers ahead of them.
Nerien reveals himself to the Dragonborn upon leaving the Mzulft Aedrome, shortly after the Oculory is calibrated. On this occasion, Nerien urges them to return to the College of Winterhold, before vanishing.
|"Hold, mage, and listen well... Know that you have set in motion a chain of events that cannot be stopped. Judgment has not been passed, as you had no way of knowing. Judgment will be passed on your actions to come, and how you deal with the dangers ahead of you. This warning is passed to you because the Psijic Order believes in you. You, mage, and you alone, have the potential to prevent disaster. Take great care, and know that the Order is watching."||Saarthal|
|"You have done well thus far, but trying times are ahead. It is imperative that you return to your college at once. You will be called on to take swift action. Rise to the challenge, and discover what you are capable of. You are on the right path, and you will prevail."||Mzulft|