Is Jormungandr Atreus Son?

If Jormungandr got sent back in time before his birth, then it's definitely possible for him to be Atreus. But then again, he could just be his actual son. If he's "born" between Ragnarok, the same thing applies (could just be his son)

Is Atreus the World Serpent's dad?

First, it confirms the existence of Angrboda and her role as the mother of monsters. It also confirms that Fenrir, Hel, and the world serpent are siblings, and most importantly it confirms that Loki - AKA Atreus - is their father.

Who is Kratos son Atreus?

Divine-Jötnar Physiology: Atreus is the son of Kratos, a Greek divine being and the former God of War, and son to Zeus, and Laufey, a powerful Jötnar Giant. As a result of this, Atreus has a tremendous physiology, making him a hybrid of the Greek and Norse pantheon.