Everyone that went to fight abroad knows that bounds between team member gets stronger. Just the fact going in a foreign country, far from everything(habit, tradition, family memeber, languageetc..), makes very quickly the people that represent boundwith every day life. And more nearer is the fight and the stress grows and the needs of your team member grows aswell for their support. A bit like in a mediaval time where warrior went to war with only his weapons and people....
....we end up having a profond relationship.... where the bounds are very similar that would have with your family rather than training partners.