Mine cried a lot from birth due to reflux. Ended up in NICU where they figured out issue and with proper treatment the crying was simply to alert us to needing to eat or needing a diaper change if we didn't detect early enough-a different cry and there were usually signs of warning before where we could prevent cry like opening mouth and pretending to try to breastfeed with the air or trying to breast feed on anything.

Then I listed to a patronizing older doctor who said we should wean off reflux meds and thickening when he was only a pediatrician and not a GI doctor. So I did and there was screaming and crying and vomit once he was off.

So for us the scariest crying was usually GI related.

Mine was a very uncomfortable baby. Cried a lot and had a very hard time falling and staying asleep. Also trouble with nursing and bottle-feeding. I didn't feel he had typical eye contact and interaction - also seemed kind of expressionless. Not a baby who was laughing and giggling a lot. (But doctors were sure it was my anxiety and he was fine.)

Also didn't really have much of the terrible 2s. I remember only a handful of tantrums, and they were pretty minor. He got into literally everything and didn't seem to approach things with the same social attention as others - i.e. other kids would be sitting, looking at music class teacher, and my kid would be trying to get at the tissue box behind her so he could pull them out.

Easy baby. Normal development on everything except he did not point a lot. Also, when I took him to the zoo and pointed at the animals he did not show same interest as his older siblings did. Otherwise, all development was normal until age 2.5 when language regression and echolalia started. Then, he lost motor milestones and coordination. At age 10, he still cannot do buttons without help and cannot tie shoes, but he attends mainstream school with an IEP.