Here's the central contradiction your baby is living inside: an Aquarius Sun wants to think before acting — to detach, observe, turn a feeling into a concept before committing to it. An Aries Moon does the opposite. Emotions arrive as immediate, full-body impulses that demand expression right now, before a single thought has formed. The result is a little one who can seem genuinely surprised by their own feelings, as if the inner fire keeps outrunning the cooler, conceptual self that's supposed to be in charge.
What makes this pairing so distinct is the fixed-versus-cardinal push-pull. Your Aquarius Sun is built to hold a position — once this baby decides something is interesting (or isn't), that conviction locks in. But the Aries Moon is all cardinal ignition: a new frustration, a new delight, a new demand, right now. That combination can look like a baby who has fierce, settled preferences but cycles through them at startling speed — committed to the toy until the emotion shifts, then completely committed to the next thing.
The Air-and-Fire mix does have a gorgeous upside: intellect and enthusiasm feed each other here rather than canceling out. Your little Aquarius-Aries actually gets more animated when they can explore ideas physically — touching, moving, pointing, protesting — not just watching. Whichever of the 12 rising signs shapes your baby's outer layer will tilt this picture noticeably: an earth rising will slow the Aries flash and steady that Aquarius detachment into something that reads as calm; a fire or air rising will let the whole combustion run much closer to the surface.