The phrase 'how far under that skin of yours' seems to elicit a brief, quickly hidden reaction from Ducky, because. That hasn't not been a background process in her. Just. Not a physical one, and likely never will be a physical one and really there's no point in considering how else that sentence could have ended.

"I do trust Mimley to come home safely. But. In the extreme case he had not, you were who I wanted beside me to consider and enact contingencies." Because Crabb makes her feel safe, grounded.