Man, I'm seeing a lot of confusion online about the 'Innocent V' thing. I think a bunch of folks are getting their wires crossed because there isn't a single, famous novel or series by that exact title. The confusion makes sense, though. If someone's asking about 'Innocent V', they're probably mixing up a few possibilities, and the characters they're after depend on which one.
The most likely culprit is 'The Innocent' by David Baldacci. That's a Will Robie thriller. If that's the book, then the mains are Will Robie, the government assassin, and his partner/asset, Julie Getty. Their dynamic is the core of the story—Robie's this detached, clinical killer and Julie's the unpredictable wild card he has to protect.
But 'V' is throwing me. Maybe they mean 'Volume V' of something like the manga 'Innocent' by Shin'ichi Sakamoto? That's about the Sanson family of executioners in revolutionary France. The main character there is Charles-Henri Sanson. Or it could be a typo for 'Innocent' something else entirely, like a fanfic or a web serial. Honestly, without the exact, correctly punctuated title, it's a guessing game. I'd need the asker to double-check their source, because the character list changes completely based on which 'Innocent' we're actually talking about.