Per wiki policy, Spoilers Off applies here and all spoilers are unmarked. You Have Been Warned.
- The name Horus' has both the meaning "One who is above" and "The distant one", which both describe Hancock's personality rather well.
She does specifically tell him that his purpose on earth is to save humanity.
- Mary says they've gotten engaged and broken up every century since 3000 B.C. Definitely over 2000 years old.
- The child is immortal. It would be an adult by the time the movie takes place, and likely off on it's own somewhere. Mary didn't mention it because a)she just never had a chance to bring it up, or b)their child has been off having his/her own adventures for so long that it's all but forgotten.
- The child is mortal. If the child were conceived and born when Hancock and Mary were sticking together, and thus mortal, the child is probably mortal as well. Once Mary and Hancock split, Mary regains her powers, but since the child was born mortal his/her powers never manifest. Mary had to give up her child so that it could live a happy mortal life.
- Any children might have only been mortal while in close proximity to Mary or Hancock. Maybe, once Mary was due, they agreed that Hancock would leave to be a guardian of humanity once more for a while, as Mary gave birth (since that was quite dangerous considering healthcare in childbirth in the past) and then raised the child to adulthood, preparing them for a life of immortality. Then, as the child became an adult, it was left to wander the earth as an immortal, as long as they never visit either of their parents for too long.
- Or the children might be mortals, but extremely long-lived, barely aging, with possible low-level super-powers. Or maybe they were simply mortal, and may have died of old age or not at this point (a normal human lifespan could stretch past the length of time from when Hancock woke up in hospital to meeting Mary again, so he may have living mortal kids).
- Any children might have only been mortal while in close proximity to Mary or Hancock. Maybe, once Mary was due, they agreed that Hancock would leave to be a guardian of humanity once more for a while, as Mary gave birth (since that was quite dangerous considering healthcare in childbirth in the past) and then raised the child to adulthood, preparing them for a life of immortality. Then, as the child became an adult, it was left to wander the earth as an immortal, as long as they never visit either of their parents for too long.
- Better yet, Michael Myers is who this kid was destined to become, but in this universe/timeline/world, his bullying never escalated to sociopath serial killer, because he not only knew of at least one incredibly potent "good guy" to either inspire some sense of wanting to do good or at least some fear of being punished for doing wrong, or, at least, because even his relatively minor bullying was dramatically punished in a way that is able to make him totally rethink the path his life was taking.
Mary is more powerful, but not as tough, Hancock survived multiple gun shot wounds, beatings and a knife wound while his powers are on the fritz, Mary 'dies' from being shot once or twice.
- Or maybe the wounds that Hancock took just luckily happened to be less severe internally, missing organs and the arteries, while Mary's wounds are more severe, by coincidence, and the weather power is something they both can do. Hancock just hadn't realised he could control weather, having only discovered his more obvious powers (toughness, when hypodermic needles won't pierce his skin, strength, when he never finds anything too heavy to lift ever, and flight, after falls from great heights instinctively have him reject gravity - which is why his flight is wobbly and indelicate until Ray and Mary persuade him to think a lot more about how he flies).
-Hancock and Mary are claimed to be both brother and sister AND husband and wife.
-Every time they seperate, the situation involves Hancock being harmed..like Osiris.
-Hancock's only clue to his past was a ticket to see Frankenstein...a film about a being who is pieced together out of dead body parts and brought to life once more...like Osiris.
-Aaron has eagle/falcon imagery in every scene he is in.
-Aaron's birth mother died in childbirth....not exactly a common occurence in modern times.