The only extended clip I can find from Southern Comfort on Youtube is this one. It's been posted by someone who is keen on the music (that's another perspective) so it really doesn't cut in and out where I would have done.
Anyway, this is my analysis of what is going on in this particular clip. If you want you can judge whether I'm seeing too much. It was the cross-watching against Aliens that really opened the scene up for me.
WARNING - the clip includes graphic scenes of an animal being slaughtered, for real. It's 7 minutes long.
The blond soldier is Spencer, the clever one, who has committed by this point to saving the life of Hardin, the tall dark one. The two of them have just escaped from many days being hunted by locals through the bayou, and all the rest of their platoon have been slaughtered. They have come upon a small isolated village, where there's a festival going on. They are unarmed (no ammo left) and exhausted. The baddies are close behind them.
In the first part of this scene Spencer has worked out how they can stay alive - stay in the centre of the crowds of people, because the baddies can't touch them there. He spends most of the scene trying to model this to Hardin, who takes no notice. Spencer's attention is always coming back to Hardin. Hardin turns his attention outwards, and sees death closing in on them.
Hardin wants to fight for his life, even more than he wants to live. Even though there are lots of baddies, and they are armed with guns, he steals a big knife and goes into the deserted huts, to fight them all - a suicidally stupid thing to do.
Spencer sees what is happening. Although he knows it is insane, he leaves safety, unarmed (the gun is empty) to try to rescue Hardin. The way it is presented is quite understated, but it shows a terrific change in Spencer who has more or less done nothing as one after another of the platoon are killed off by their own stupidity. Look at Spencer's face at 6.30. I think there is a big parallel with Hicks following Ripley into danger at the end of Aliens.
It's not the scene I'd have picked to demo the relationship, but I think it shows the asymmetry between the two men. If it was a simpler film the relationship would have been (for instance) co-operative on both sides, and that was how I thought it was when I first watched it. But in fact it's much more morally fraught than that. Hardin is a violent self-destructive arsehole really, and Spencer is a lazy cynic.
Sorry I keep posting about this - I expect you get this fascination sometimes with a book or a film or something, and I tend to externalise it when it happens to me. It helps me to formulate what I really think.