My vampires are pretty affectionate towards one another—namely because most of them come from times and cultures which were not afraid of touching, the way modern American culture is. They are also instinctually attracted to the scent of their own kind—which is part of the reason why they live in groups—and this attraction is even more intense among people who are related by blood; they are always most attracted to their sires, their siblings, and their children—followed by more distant relations (grandsires, grandchildren, the children of their siblings, and cousins).
When they are with others of their kind—especially people they are close to either through blood or choice—they generally feel a sense of safety; touching or being physically close reinforces this feeling. This is part of the reason why they put a great emphasis on being able to trust others of their own kind; they are all naturally prone to trusting, and the worst thing any of them can do is break that trust.
However, just because they are instinctually attracted to their own, that does not override other concerns. They can still dislike—even hate—each other for legitimate reasons. In fact, their hatreds seem to be every bit as intense as their loves/friendships.
Touching foreheads is considered an intimate gesture—something done between close friends and family. Anselm does this to Micah when he’s trying to calm him down and encourage him to be patient. After all, it’s pretty hard to be upset when you’re that close to someone else. Joshua also does this to Micah when he prays for him. It is supposed to be personal—just between the two of them.
Kissing the forehead is a gesture of affection that is usually—although not always—reserved for superior to inferior—including parent to child. Anselm, Micah and Isaac all kiss Kalyn this way, and it’s meant to be construed as paternal or brotherly. Joshua also kisses Micah this way, and it’s meant to be both paternal and a form of blessing.
Kissing the cheeks is a common greeting among vampires who are friendly with one another. There is a subtle hierarchy, though, in that the person of rank kisses the cheeks of the lower-ranking person (in the case of close friends, they would kiss each other simultaneously, showing that there is no recognized rank among them). You see this play out twice in the first book: when Anselm and the others go to Charleston, Anselm very politely waits for Marie to greet him. Anselm is an acting leader, and in the strictest terms, he was her equal at the time—not to mention that he and Marie are very close friends—but because he seeking her help and admittance, he does not offer to greet her. He willingly puts himself in the inferior position. This, in turn, puts pressure on Marie to offer the greeting—to not do so would be rude to both a fellow leader and a friend—but it also implies that if she greets him, she is accepting him, and, by extension, everyone with him.
The other time this type of greeting occurs is when Joshua comes to visit everyone when they first arrive in Jerusalem. He greets both Anselm and Micah in this way. They would never think to offer him a greeting first—that is always his prerogative—but in kissing them, he is saying that they may be friendly with him and not stand on the usual ceremony.
For people Joshua is not close to, he will offer to shake hands (he usually does this when meeting with people outside their culture), or he will slightly incline his head to the other party. In fact, the latter is his usual response when an inferior (namely a Yaechahre) bows to him in greeting.
Kissing the lips is a direct acknowledgement of someone being an equal. Of course it usually has romantic connotations, but Joshua does kiss Kalyn this way—in private—and it is not a romantic gesture. She doesn’t know it at the time (he’ll explain it to her in the second book), but in doing so, he is acknowledging Kalyn as his equal, meaning that when they are in private, at least, she may speak her mind and be his friend, rather than his subject. To kiss someone on the lips in front of others is to publicly acknowledge that person as your equal (meaning you expect everyone else to treat your friend as they would treat you).
Bowing is a gesture of respect from an inferior to a superior. Among the Canichmeh, they typically only bow to Joshua and also to the members of the Council when they are in session. The Yaechahre usually bow when being greeted by any Canichmeh—although almost no one does this in their home group, where they are much more familiar and casual with the Canichmeh there. Bowing is typically limited to a bow of the head, although a much deeper bow is typically afford the Council and Joshua. For a Canichmeh to bow to a Yaechahre is a very great sign of respect (although this is just a sign of respect, not of submissiveness); it happens rarely.
Holding hands, hugging, and putting an arm around another’s shoulders has no specific meaning, but are all common gestures among the Canichmehah, simply because they are affectionate and like physical contact with one another. Anselm is especially prone to holding Kalyn’s hand when they are walking, but this is due to the fact that he has always felt an instinctual (platonic) attraction to her. From the time she was child, her scent has triggered the same sort of response in him as the scent of his own kind does, so he has always felt a desire to be close to her. Interestingly, she has felt the same towards him, and when she can get over her girlish crush (which makes her nervous and a bit silly around him), she derives the same feeling of comfort and safety being around him.
There are two gestures of submissiveness. The first, which is milder, is to bow over and kiss the hand. Anselm kisses Kalyn’s hand at times, but he always lifts it to his lips; this keeps it from being submissive, and instead is just an old-fashioned gesture of respect from a man to a woman. However, Marie actually bends down and kiss Anselm’s hand as she apologizes and begs him and the others to stay with her. To refuse someone when they beg in this way is a snub; if Anselm had refused Marie, she would have been hurt.
Micah bows over Kalyn’s hand and kisses it at the end of the first book to thank her for what she did for them and to also humble himself before her; he is acknowledging her act as something which makes her superior to himself.
The second gesture of submission is to get on the knees and kiss someone’s hand. This is the ultimate gesture of penance or pleading. To have your apology or request turned down when offered this way is the ultimate humiliation; your relationship with that person is probably unsalvageable. Anselm does this to Kalyn after she is attacked by Jonas because of the heartfelt remorse he feels. However, it is almost unheard of for a Canichmeh to humble himself or herself before a Yaechahre in this manner (not that Anselm cares much for social hierarchy).
Anselm also gets on his knees and bows over Kalyn’s hand at the end of the first book to show his thanks and respect for her. He shows more deference to Kalyn than even Micah does because, as Eruj, he was supposed to take care of the people that Kalyn took care of. She, in effect, did his job for him. Not only that, but he is thanking her on behalf of all the rest of the people in the group.