nuh uh :'> In case you haven't seen the raw, he showed a really creepy grin like Siwon is about to become his pet or something ╮(￣▽￣)╭ Just saying so that you won't get your hopes up too high :)
I am not getting my hopes high but i am slightly hoping for a positive development in the character.
But there is so many different ways to interpret his grin because Xuan is an incredibly unpredictable character. There really isn't any way of knowing until the next few chapters, but basing on earlier chapters (going by his inner turmoils about Siwon)... it could be seen that he is very excited because he thinks Siwon is "willingly" going to become his. I think he genuinely likes Siwon even if it is in a twisted and unhealthy way.
But by making that bet with Jinha, it could almost mean he is looking forward to Jinha's despair/reaction when he realizes Siwon willingly chose him.
For right now, there really is no way of knowing. But I'm in agreement with OP, this is good potential for character development for Xuan.
I agree.
I am getting a feeling that Seonyun is gradually genuinely liking Siwon..