IcingDragon; "Force Feeding Plots"
Michelle "A Players Guide to DMing"
Jason "Evil Party Cohesion"
Jason "Labor of Love"
Sean "Challenging the Superparty"
Sean "Plot Threads"
Sean "Secret Societies"

Evil parties are kind of an enigma. Evil characters, more than any other type of adventurer, are solitary creatures, particularly when it comes to undead. They have a tendency to stalk the nights alone, mostly because evil tends to chafe against other evil- especially when faced with opposites on the law/chaos axis of alignment.

There are ways to get around this. A great resource I've found, which has been under my nose for quite some time, is the Guide to the Sabbat, a sourcebook for Vampire: the Masquerade. There are parallels that run between a pack of Sabbat vampires and any other evil (and particularly evil and undead) party.

Despite their solitary nature and their frequent ambition, evil characters have very few options for those they can socialize with. Good characters will invariably refuse to treat with them, while neutral characters may find them distasteful or their methods a step too far. This leaves only other evil characters to associate with, despite evil's tendency to work against itself more often than not.

Regardless of this, no evil character, no matter how misbegotten, forsaken, or vile, can completely sever the tie they have to things that are "good", or "normal". They have trouble leaving behind what they once were. They desire some of the same things that characters of other alignments desire. They want power or wealth, companionship, maybe love, or at least the feeling that they're not alone. Being alone, for an evil character, spells more than just lonliness- it's danger. There's little safety in being alone.

So, an evil party can, should, and almost must act with a pack mentality. A group comprised of undead characters will find this easier than other evil folks, as they are already united by something in common. Simply put, evil is an individual thing. It's rare that someone's whole family is evil. It's more rare that an entire society is evil. Evil characters must have left family and friends behind to try to fufill their evil ambitions. Even in an evil society such as Xaiphan, friends are hard to find because the evil there is almost always in conflict with itself (in a subtle way).

True friends are hard to find. And while trust can be an issue among evil peoples, if it's built, it tends to go deeper than trust formed among neutral or even good people. Five evil undead can find companions, and even a surrogate family to replace the one they lost, among each other.

This unity (whether for a purpose like accumulating wealth or retrieving an artifact, or simply to bypass lonliness and fight ennui) does not imply that the surrogate family isnt dysfunctional- a group like that may be one of the most hellish conglomerations of savage personalities in the multiverse- but some level of sympathy always exists. Who else could possibly understand the weight of an evil character's troubles?

A "pack" mentality can also serve as a spiritual guide. Evil clerics (such as Jareth and Cyr'ri) help to lead the individual members of the party on a journey into what it means to be evil, and particularly what it means to be undead. The family that prays together stays together, and there are evil gods out there. The cleric of the party provides a spiritual backbone on top of the healing and magic. They'll tend to be careful about being too preachy, but still, the presence of an evil cleric should be comforting to an evil character. The evil priest is one who the rest of the party can see as someone they can TALK to, about anything, because they are a confidante. Even someone who doesnt worship a deity at all, or worships a different deity (so long as it's an evil one) can talk to a cleric- they are the shepard of the party. This group will have seen one another at their worst, and they'll depend on each other to help them deal with any spiritual dissonance they might encounter.

Obviously, the party offers protection, as well, even going beyond "fighter stands in front, wizard stands in back". Being that evil folks loathe almost everything that's not very similar to them, and their frequent competitive urges, it's not surprising that evil often runs afoul of other evil. In an evil party with a "pack" mentality, the members watch each other's backs mutually. The trust pays off. More so when the group doesnt just have to fear other evil entities, but when faced with marauding paladins, enraged metallic dragons, and the wrath of angelic might, the group offers it's members safety in numbers.

The group is also the equivalent of a social circle, as mentioned above. It adds a lot to the credibility of an evil character when he or she has four other equally powerful and equally evil characters to back up what she says. Not to mention there will always be at least as many things the party has in common as they have differences. The party's wizard might be fascinated by the cleric (particularly if this is a cleric of an arcane-oriented god, such as Vecna). Rogues and fighters can learn from one another and improve the both. Soon, the party learns to rely on one another, so long as they are confident of their place and role in the group. The party can't track without the ranger. They can't pick locks or disarm traps without the rogue. They can't dispel magical obstacles without the mage. Their healing is limited without the cleric. This puts at rest a lot of the fear of backstabbing among evil parties.

Of course, in the end evil creatures still pursue their own agendas, make their own contacts, deal with people they prefer (which should be the party above all), and otherwise lead private lives (or unlives). The role of the individual is equally important to the role of the party. It's only when the party takes a backseat to the individual that cohesion is in danger of breaking down. It's a careful balance, and players are as responsible for maintaining it as the DM, but when it works... it works like a charm.