Fantasy series, two kids try to save the world form the evil king. the boy is bound to a dragon via a crystal on the forehead

[Joshua]

About a Boy and his sister i think and the boy is bound to a dragon via a crystal on the forehead there are two worlds i think maybe more with an evil king or ruler or something and his evil daughter blah blah its all might be's but its all i can remember there were creatures in a swamp they were able to befriend as part of some sort of resistance against the king per say. thats all i can thing of now it might have some sort of zone thing not 2 worlds.

[Joshua]

By zone i mean they use some sort of portal or gate way to enter a sort of alternate world sort of where the alternate world is ruled by the kings daughter

[Lobstergirl, au gratin]

Jack, as you saw in the popup box when you posted your comment, please put some plot details in your header (in addition to the genre). This makes your query a lot easier to solve.

We also need to know when you read this.

[Lobstergirl, au gratin]

Joshua, are you still looking for this or did you find it?