You know what's most funny about Brenok? He is a clever one, open-minded, with revolutionary ideas (his propositions on how to go on with their political agenda actually shocked Gul Tarkan, who didn't know Brenok at all), in some way smarter than Jarol (not that she's stupid, just... hard and slow to change), but he is sooooooo young. He's only 31! And others - older others - listen to him! He makes an impression.
He's an engineer, so it's easier for him than for Jarol to see that if something doesn't work - you have to fix it! That's how he thinks - fix it! And being under Jarol's command lets him think independently, not just precisely follow strict orders and not think too much about them much.