@spamqualle From what i know after checking in chapter 48 they made a deal. He helps them and in return that wizard tries to find a way to remove the curse (which he can't really do since it's not simple curse but some demonic power) and also tries to find a way back to his world (The demonic curse shouldn't have any power over there and the curse would be undone, too).
He isn't able to beat them all, either as seen against the fight vs the mecha golem.
It should have taken him around 10 years to get his full power, which is one level below the golden dragon ( i think?). Although now with his papa helping him, he might get even stronger.
He probably won't lose his power, since the curse 'took it away'. But removing a curse doesn't really take anything away and just releases what was taken and changed, i think.