It's a couple of years after (GOW)Ragnarök, you(Kratos) and Mimir are somewhat excited to see your son for the first time in a couple of years, Atreus Has grown their hair out, and now goes by they/she, but the problem isn't that Atreus is a girl, The problem is that she now looks alot like Calliope, your dead daughter, Atreus doesn't know about Calliope.

Angrboða holds Atreus hand tightly as Atreus speaks

"Hello father.. long time, no see." they chuckles awkwardly