T'amo E T'amerò (слэш)

"That's totally unexpected Yuuri, with due respect. You're a little hard to be with from what I recall." Keith 'With a personality like this you'll stay single even when we meet in ten years. No one would want to be with a pathetic person like you!' says. And suddenly Yuuri is very determined to go on with his lie, giving his best performance and the biggest surprises. "I'm very curious about this relationship!"
Without further thinking, Yuuri says proudly, "I bet you're surprised, and you'd be even more surprised to know that my boyfriend is non other than Viktor Nikiforov."
What kind of disaster has he just got himself in? It's understandable to hold a deep grudge to the obnoxious ex who broke Yuuri in every way, but to claim that he's in a relationship with not only his work rival who probably doesn't stand his guts but also is way out of his league, that's too much.
 
An au where Yuuri and Viktor are kind of enemies but Yuuri needs him to pretend to be his boyfriend to tease his awful ex