Trust

To anyone who wasn't an N-Tek agent, the word "partner" conjured up images of a romantic relationship. That, or it would click as a spy term for those who watched such shows as Alias, Spooks or possibly any James Bond movies. As a result, many of the N-Tek agents had to catch themselves before accidentally calling their partners such. To some agents, though, the word 'partner' had a different meaning.
To them, it meant confidence, hope, trust. Quite probably one of the very few people who'd know about their true life, not just someone who knew what went on between 5PM and 9AM (if they kept to a normal work schedule). To them, having a partner was someone who you could trust with their life, more often than not literally.
A partner was someone who knew your every move, who could distinguish between the body language meaning 'worry' and 'anxiety', who could be counted on in an emergency. One person had referred to it as something akin to the psychic bond twins are said to have, and he wasn't far wrong.
Both partners could be blindfolded and wear headphones relaying sounds in stereo to allow them to identify where a target would be, and they'd both move in sync, attacking with perfect harmony and no faults.
It was a bond deeper than that of friends, family, even love, and was extremely difficult to come by, yet people at N-Tek were displaying it nearly every single day without fault.
Trust like that was unimaginable to the average person.