I'm going insane thinking about Zevran and his life as a Crow before Origins, connecting dots that were never meant to be connected, but it's so good, you don't understand.
Because Zevran and Taliesin have known each other since they were children and if their training killed 16 other children, their training must have been awful, so you know they were close and genuinely cared about each other, were probably each other's first love. And then they meet Rinna, just a few years later when they're like 11 and she's a bastard, elven blooded child of the prince and thus fascinating to two poor children, and they're all thrust into the life of assassination together.
They're thrust together into dangerous work, made even more dangerous with the politics surrounding Rinna, is it any surprise that the three fall in love? And maybe it's childish, a little naive, but it's still real, still safety and belonging outside of the whole system of the Crows.
Also, a little bit of headcanon, but as Compradi, Zevran and Taliesin don't really have a lot of expectation of upwards mobility, not compared to people who were born into the Crows. Compradi can technically advance to leadership if they're good enough, but the 'heirs' of a house usually don't let them live long enough to make a good attempt.
That's why they don't really excel until they meet Rinna, who wasn't born a Crow but as a daughter of the Prince does have some manner of political protection that Zevran and Taliesin just don't have. She has ambition and idealism that her position will let her protect her friends/partners/lovers (her family) and let them all advance into a better place. She knows they'll never be safe in the Crows, not really, but she can make them safer, at least. And it works.
And they're good together, really good. But then.
Rinna's 23 and someone has put it in her head that she could be put forward as the legitimate heir to Antiva and she sees opportunity. And then Prince Claudio Valisti, third Talon, learns about this and his house has another name to put forward and he sees Zevran, the man that killed his best friend years ago (Luis, Isabela's husband), and he decides to kill two birds (ha!) with one stone.
He frames Rinna for betraying the Crows (betraying Taliesin and Zevran) and sets it up so that they're the ones to kill her. And they believe it! Because they're Compradi, they're not as valuable as her, she didn't tell them, they believe that she was using them to advance her station and then she was going to leave them behind after years of working together, loving each other.
And then after Rinna dies, Claudio looks Zevran in the face and says it was all a lie, Rinna never betrayed the Crows, and that Zevran is nothing more than canon fodder, the Crows don't care, and one day his usefulness will be up and they'll kill him too, just like Zevran killed Rinna.