In episode 24 of Durarara!! ×2 (the last episode of Ten), Izaya identifies himself to Vorona as one of her previous clients.
What did Izaya actually hire Vorona to do?
It was Yodogiri who hired her and Slon to abduct Awakusu Akane, and I don't seem to recall having been told who hired them to attack Anri (and in any case, I don't see what Izaya's motive for having Anri killed would be, though his motives are admittedly a little bit opaque at times). Am I forgetting something?
Unfortunately, it was Izaya that ordered them to hurt Anri, which happened in the Akane arc.
Varona arrives at their hideout and Sloan tells her of another job given to them by Izaya Orihara to neutralize, but not kill, Anri Sonohara
As for the reason, it was not mentioned, but it was probably to make sure she would not interfere with Haruna Niekawa as she controlled the Saika children.
Another reason is that Haruna Niekawa wants revenge on Anri and also wants to know the location of Takashi Nasujima. Izaya has promised her both. So it would be logical for Izaya to use Varona to fulfill his promise to Haruna.
