Okay, so this is really early, and its a longshot, but bear with me.
In It Hurts, colors mattered a lot. Pasq's eye and hair color determined how human he was, as well as he fulfilled he feels emotionally or whatever. Green was representative of happiness and Aurora, etc etc.
I think in this one, its the weather or something. Keep an eye on the clouds - Pasqualo looked at them directly in comic 8, and they've been getting progressively darker. Then they turn a sort of pinkish color at the end of 8 - maybe because of the bonding with Allison?
Posting this now in case it comes up later.