In the first half of the anime, I saw strictly Viktor x Yuri due to body weight, age, height, status, & the fact that Yuri is a virgin while Viktor has dated before.
But by the end, I can kinda work with Yuri on top, with the angle that Yuri seems to be turned on constantly & is becoming more of a man & less of a boy as his confidence in himself builds, & Viktor is usually more compromising & suggestive on issues rather than being insistent, which is like being submissive. Rather than being the one to take action, he asks Yuri what he want's to do.
I've always believed Yuri is the seme too. Re- watching (again lol) just look at the pictures at the end of episode ten )pure seme looks from Yuri ლ(´ڡ`ლ)
I've always ALWAYS seen Yuuri as the seme and Viktor as the uke, so I'm so thankful for this dj. It's such a relief that at least I'm not the only one who saw Yuuri as more masculine and Viktor more feminine, the only problem was that they were a tad out of character.