At the end I needed 40 likes, my error was that speedrunning every time I restarted from when you fight Roushk to the celebration event I made the same choices and every time I had 39 likes. It has all to do with what you were asking, Thank you! When you say that you imprisoned him while you were finding a cure, makes me think that you can capture Roushk before you talk to Othra about the lake and if keeping its existence a secret, because after that point you know how to cure him.