Here he gives some guidance for casting some of the characters in a film adaptation of the novel:
Casting Crossover the movie actually isn’t going to be that easy... or at least not if it’s done well. The supporting cast could be relatively straight forward, but Cassandra Kresnov herself is another story -- maybe someone reading this would have a better idea than me.Read an excerpt from Crossover, and learn more about the author and his work at Joel Shepherd's website and blog.
Cassandra (Sandy) is an android, but unlike anything Hollywood’s ever seen. She was created from technology that copies human beings in synthetic form, with appropriate improvements. So she’s basically human, only made of different stuff. The ‘improvements’ are that she’s death on legs, the ultimate killing machine. The catch is that the same added intelligence that makes her the most deadly of her kind, also makes her more emotional, more vulnerable, and sends her in search of a life free from violence (that bit doesn’t work out so well for her though).
The actress playing Sandy would need to be very pretty (no shortage there) but would also need to have a strong physical presence -- what Sandy can do is pretty scary, and the intimidation factor needs to be convincing. Unfortunately Hollywood actresses are encouraged to starve themselves more and work out less, which limits the pool. She also needs to be capable of abandoning all the standard cliches of ‘sexy female action hero’, because Sandy doesn’t really understand any of them -- despite her active libido she’s not the type to seduce the camera with sultry poses, and as a life-long soldier, she barely knows a mini skirt from a ball gown. Not that she’s not intrigued by the difference, as she’s intrigued by all civilian and pointless things. It’s just that she is what she is, and isn’t going to feel any more comfortable wearing silly things than a dog would be happy wearing rollerskates.
Sandy has a curious combination of wide-eyed innocence and worldly cynicism, disarming self-deprecation and lethal confidence. So she’d require someone who can not only look convincing while kicking ass, but who can really act, too. In other words, I’ve really no idea who might play Sandy, but whoever she is would have a lot of fun.
Supporting cast... well Sandy’s new best friend Vanessa Rice is fair game for any actress who typically gets cast as ‘girly’ or ‘cute’, and is sick of it. Natalie Portman could do it. Ari Ruben would only make an appearance if there were a sequel, only entering the Cassandra Kresnov Series in the second novel, Breakaway -- but he’s the only character who was partly inspired by an actual actor, Adam Goldberg. Anyone who saw his character in the short-lived TV show Relativity might recognise some of Ari’s mannerisms.
As for the Director... well, anyone who understands that the story matters more than the FX. For all the cool action, the fastest way to screw up the movie would be to make it ALL ABOUT the action. We all know Sandy can kick pretty much anyone’s butt, the real drama comes from her trying to figure out WHOSE butt, and why, and can she live with herself afterward. This isn’t some shoot-em-up where the primary drama is whether our hero will run out of bullets. I don’t know how many Directors know these things, but there are some out there, certainly.