1) Petro and his only brother Matvei are twins, with Matvei having been born first by forty-five minutes, making Petro the youngest of all his siblings.
2) Petro still maintains close ties with his sister Galya, who, like him, became a spontaneous vampire, most especially as their other sisters and brother are all dead from old age.
3) Petro is a bisexual whose first few relationships were with girls and he lost his virginity to his first girlfriend at the age of fourteen. None of them worked out, and the third girlfriend cheated on him with a football player. After that, he pretty much gave up on relationships up until he met one Olik Mikhailachev and the two have been inseparable since.
4) Petro's mother Katarina disapproved of Petro's relationship with another man, even as she herself was the daughter of lesbians. The reason she cited was because she believed that a man like Petro wouldn't make for a good match with a gay man (as Petro is fairly "masculine" as far as that goes). Katarina thought that Petro was better off with a woman, even though Petro had tried women and found that as a bisexual, he had a stronger preference for men.
5) Petro, like his cousins Kliment, Vadik, and Maiya, was promptly disowned as soon as his grandmother Tanya found out that he was a vampire. Fortunately, Petro was already married into the House of Dimitri and living with Olik, his in-laws, and his three children and could care less about what his grandmother thought. He of course, was disowned by his mother and a few of his sisters as well, but his brother Matvei, and sisters Halinka and Galya did not disown him and he kept in touch with Matvei and Halinka up until they died of old age.
6) Petro is the only one who knows that Olik's "intuition" is actually a telepathic ability. Olik tells him that he'd had the ability to read others since he was very young. Petro doesn't freak out about it, as Olik has been the most meaningful relationship that he'd ever had. Now that is some serious love there.
7) Petro is not an overly-mushy kind of guy in public (he's super-shy), and isn't fond of PDAs of any kind. He is perfectly happy with a "reserved" relationship like what he has with Olik where their wild side only comes out in the privacy of the bedroom.
8) Petro was horrified, just like everyone else, at the treatment his cousin Kliment had suffered at the hands of his first husband. He didn't question Bogdan, but only because Olik smiled at him and assured him that Kliment had the right man in his life now.
9) Since Jay's death, Petro has made more of an effort to be a good cousin to Kliment and keeps checking on him regularly.
10) Petro does make the occasional trip to town. In one such trip, he saw the girl who had cheated on him and it was a night he was out with Olik. He finds out that she got pregnant and was living on welfare checks because the father is a deadbeat. Petro would have felt bad for her if she hadn't made a homophobic comment over the fact that she had seen him on the dance floor with Olik.
I should mention that it's pretty much a given that Olik and Petro are going to make their fair share of appearances in Full Circle, and that Petro has a bigger role to play, in part because he is Kliment's maternal cousin and he is doing what the rest of Kliment's family is doing; looking out for Kliment's welfare.