>>186936969>The demon baby's feelings
First of all, we need to consider the two parts of the child, the physical body and the astral body. The physical body got absorbed and transformed into Griffith when he reincarnated and it's what caused his heart to move when he was watching Guts fight Zodd. However, he treats the incident like the last remnants of what the baby can do and after that he's convinced that he is fully moved past them and can't be affected again. Then there's the Moon Boy, which is most probably the astral body of the child. He looks like Guts and Casca's child and they had the family moment in the hut which was really emphasizing it in a "what could have been" way. He is also watching over them like the demon baby used to and can only appear during a full moon, when the astral phenomena are the strongest.
I predict that Griffith himself won't give a shit about Guts and Casca anymore and that the physical body of the baby won't have an effect on him anymore either, but the astral body will eventually do something to help fight him. He might possibly claim his physical body back from Griffith which will weaken him somehow and give Guts the chance to beat him.