The author was obviously talented – and the agent was working on this, his first novel, with him.
His style was good and his plot was very different and interesting, I said. However neither of us felt that the characters' motivation shaped the plot realistically.
The agent and I discussed how we thought he should change things, and it was exactly what I enjoy doing most, taking a novel and extending it, throwing out ideas and bringing more coherence to the work as a whole.
Nothing beats talking about a novel, thinking through a character and adding elements to a plot. Why not get together with another author and take it in turns to just play with the ideas you have. And if you've registered on this site you can always search the user profiles to find other writers who are working in a similar area to yours.