As part of the nether update theme, I think it would be a cool idea to add a new hostile mob called the demon/fire bird(unofficial). This would serve as a new threat that would spawn in the more “lively” part of the nether, including the nether forest and maybe more. They could have a drop that could give the player a certian material to help stay alive in the nether. They could also be hostile towards undead mobs(“acting” like vultures) or certain living mobs, i.e. piglins, blazes, etc.
Another cool idea of this mob would be the transformation of it as a pet being the only nether exclusive pet, which in my opinion should be something in this update. For this “form” it would be neutral unless provoked and taming it would require some kind material/item maybe. I know LadyAgnes stared that the mc team tries to teach the user a lesson when it comes to mobs but come on its not 100% realistic( taming wolves, hit cows, horses, etcetera and not being kicked back at, ocelots, etcetera). If you like this make sure to vote for it and share it.