That is the catch 22 of having a hero or villain be the leader of a nation. It only works if they are not used every month because it limits storytelling if the character has to always be around to govern their people. At this point I would be happy if Aquaman was never the king again and was just the protector of Atlantis and seas. Same with Namor over at Marvel. It just gets boring with the constant "gets the crown, loses the crown, get the crown back" cycle.
I would rather see Aquaman abolish the monarchy once and for all and just set up a ruling council made up of all the different races under the sea with each citystate having a governor the reported to the council. Make the council up of members of the normal Atlantis/Poseidonis folk, the merfolk of Tritonis, the blue skinned folk of Lemuria, the manta people of Hy-Brasil, the dark skinned people of Tiapallan, the green skined barbarians of Marrzon, the magic users of Thierna Na Oge, someone from Noble's grey skinned people, and whatever other small city states exist under the sea. Having all the different races under the seas having to interact all the time could create just as much political intrigue without the constant "fight for the crown" stories.