I think everyone is just jumping into conclusions about Viktor, being the antagonist or just an asshole (but you can’t just believe that everyone will be a perfect innocent soul, all the characters will have their level of greed and of egoism), when we don’t really know his true intentions!
I don’t believe that Viktor will hurt, use or leave Yuuri in any way possible, because just watch the images of the ending, you can see that they have a bond! a really deep relationship by just looking at their expressions and their actions , maybe Viktor intended to use the training of Yuuri as an opportunity but that doesn’t mean that he will do it, maybe he will change his mind after getting to know him better.
And also, yeah, poor Yurio, he’s only a kid, but keep in mind that if he didn’t lose, we wouldn’t have chapters… I have to remind that YUURI is the principal character, so the story has to be centered on him and if Yurio had the victory it would ruin a little bit the point of the story. Also, we can see that Viktor wanted him to feel the song, his agape, but he decided to center on his skating and that’s why he lost, even if Yuuri made a mistake he didn’t stop feeling his Eros and he had the victory!
So please stop just trashing a character that we don’t even know a single bit! Yeah, it’s true that he didn’t handle the situation very well, but maybe he didn’t worry because he already knew that Yurio wouldn’t give up just by loosing! I mean he could just have forced Viktor to go to Russia because of his promise, but instead he decided to risk his chance of competing against Yuuri, it’s the way it is, that doesn’t mean that we aren’t going to see this character again or that he won’t have the support of another!
Well that’s only my opinion…