If we look at the last chapter of season 1 we can see a man beside the first prince and I think that man looks a lot like uke and there is also a scene of someone hanging I think that also 1st prince so what I'm trying to say I think 1st prince also liked uke and seme knows about that so he maybe that's why he killed him but as we know he's back and all but looking at seme it might be true but I can wrong
If we look at the last chapter of season 1 we can see a man beside the first prince and I think that man looks a lot like uke and there is also a scene of someone hanging I think that also 1st prince so what I'm trying to say I think 1st prince also liked uke and seme knows about that so he maybe that's why he killed him but as we know he's back and all but looking at seme it might be true but I can wrong