Ignotus' children will appear on the left of Room 45 on the Upper Left Section of Strange. They will run up to him and give him a hug before disappearing. Ignotus comments on this, asking Opus if he saw what just happened. Opus replies by saying no.
Atto Attacks His Children
In Room 12 on the Lower Left Section of Strange, Atto can be seen on one bar of oxygen attempting to crush Ignotus' children. The hallucination can only be seen by people with good eyes, as the sprites for the hallucination are almost fully transparent.