Casper cocked an eyebrow, keeping his hand out and up like a challenge as he listened to Richard's answer.
"A pilot huh? Shit you guys are everywhere.  And how the hell are you a pilot, you're to freaking big to fit in a cockpit." His tone of voice was disarming, light hearted but his eyes were still fixed on Richard's and the curve of his lips as he talked clearly said 'shake my hand or be my bitch'. 

Ground troops famously did not get along with pilots, and Cas was no exception.  It was competition, animosity, and the general one upness that came in a military. Even with friends like Tess Casper still competed just in a less blatant and aggressive manner.