I would make Sonar more like a Doctor Doom character. He has his own country, so why not? However, I'd make him more sympathetic and less egotistical. At first he would be a freedom fighter, attempting to take over Modora from the fascist/capitalist regime that starves its people. To take over, he needs an arsenal. To get such weapons, he attacks S.T.A.R. Labs and acquires sonic weaponry to help in his crusade. Green Lantern would be the one to answer the distress call and they'd have a scuffle. It would be during this fight that Sonar learns that his sound based weapons have the ability to disrupt the concentration of a Green Lantern. Most of his beginning stories would be about building an army to take over Modora. Sometimes he succeeds, other times not so much, but each endeavor brings him closer to conquering Modora in some way.
Once he actually succeeds, his regime is respected by his people and there is some semblance of peace. This could be where we find out that the previous regime was put in place by some American group, either in the government or outside of it. We could even look at Sonar's previous appearances and fill in the gaps to make the continuity work. I would even find a spot for 90's Sonar to fit in there as his royal body guard. Maybe Modora could be home to old rogues of Green Lantern who want a safe haven. Due to its sovereignty, Green Lantern is unable to pursue them once they've reached Modora.
I also want more Evil Star. He was briefly brought up during Johns' run after GL Rebirth and it would be interesting to delve deeper into the connections between the Kroloteans and him. That happened, right? I can't remember that issue, but I could have sworn they mentioned them being his Starlings. Either way, I still would like to have Evil Star come back as a real threat.>>102142125
I could at least see a crossover with GL and Aquaman with him as the villain.