Dragon Mounts Mod allows you to hatch previously useless dragon eggs

Now you can get some use out of the egg you win from defeating the Ender Dragon. You’ll simply need to place the egg and right-click it. It’s best to place it in an enclosure you’d like to keep the dragon in. Over a great length of time it will eventually hatch into a baby dragon.

It will grow on its own and once it does grow up it can then be tamed using raw fish. Then it will follow and protect you just like dogs and cats. And you can train them to sit by using a bone and right-clicking.