The only key elements to maintain are 1) Hellboy has a mysterious and extraordinary place of birth and 2) Hellboy was raised by good, ordinary people. That sort of work can be done in an opening
Hellboy 2 is really good, and remains one of my favorite movies ever right next to the first Hellboy. The reboot imo was a lot of wasted potential, mostly because they tried to shoehorn too many characters and storylines from the comics into one movie and it ended up not doing any of them justice.
IZvck.