there's no who, why, what, or when
Malos wouldn't lie - he wasn't sure he could, even if he wanted to, though Amalthus was a pretty good example - he'd been anxious to meet this Prince Addam ever since he'd first heard about him. Speaking of Amalthus, he knew his Driver didn't do anything without a very specific reason (this certainly wasn't a universal human trait), so choosing Mr. Origo to be the Driver of Malos's partner had to have been a calculated move.
Based on what figures, though? Strange, basically unjustifiable political play? Scientifically curious geneticism? Pure dumb pretty-boy luck?
I thought Tornans were all boring, plain-faced Armu-herders.