By reversing various Group Bonding Techniques, you can adjust how fast the group's ties coalesce.
For instance, the group could undergo shared ordeals, but one of your NPCs could have different purposes than you (the lead character) possess. Thus, in some ways, you'd feel like that NPC is part of the group, but in other ways not.
This was done in Star Wars Episode IV. Han Solo slowly becomes part of the group by going through ordeals with them, and because he has chemistry with Princess Leia (mostly using the Chemistry Technique of Fighting).
His purpose to make money is very different, however, than that of the group. Therefore, in some ways he's part of the group, but in other ways not bonded to them at all. This very gradually changes, but his bonding isn't complete until the very end, when his purposes and the groups become identical.
You could start a game with a number of people who work together toward a goal, but they'd have no feeling of Group Bonding. That is, there's no feeling of the group having its own collective identity. And then the "group feeling" could grow, as techniques like those in this chapter are slowly introduced. Anyone who has worked on a political campaign, or who has gone on a rafting trip with strangers, or who ever joined a Boy Scout troop or a fraternity, has experienced this kind of Group Bonding.
The point, though, is that you can get a little fancy with the techniques by regulating the speed at which a group comes together or falls apart, or by slowly bringing in a new member or pushing him or her out. My guess, however, is that, in most games that involve the player being part of a squad or other group, establishing Group Bonding early on will probably be the chosen route.
Whether you're trying to quickly establish Group Bonding or whether you're getting a little fancy with the techniques, making a game player feel that he or she really is in a group can heighten that player's emotional engagement in the game.