But you should. He knows you and when you least expect it he may be by to offer you a deal. Sometimes you can find him at the pool table, sometimes sitting at the bar where the bartender inexplicably ignores the fact that he's drinking out of a flask he brought himself. Other times he might be at a blackjack or poker table in a casino. Anywhere really that he can find someone down on their luck. Someone willing to do anything to accomplish their goal. In some cases he'll even come looking for you. He'll offer you whatever it is you most desire and the most he ever asks is that you shake on the deal. Do yourself a favor and refuse. No one ever benefits from Jack's deals but Jack. And maybe sometimes the Fears. They must gain something from at least some of his deals because it isn't unheard of for Them to be the means of accomplishing the deal. An enemy torn apart by the Rake, a desired lover controlled by the Wooden Girl, I'm sure you can figure out how he would return a dead loved one (and that is why I will never be tempted to make that deal with him). He's also been known to help along the schemes of some servants. Some of you may remember Doc Wally exposing Aura to him. I'd link to the post but the blog seems to have vanished. All of the blogs associated Doc Wally's scheme have. I fear the Quiet got them.
So, how do you spot Jack? The first clue is the name. He always goes by Jack (although I'd be worried by any variant on the name if they fit the rest of the description). Usually there is some sort of nickname attached, although he may not give it unprompted. Common names are Jack the Hand, Red-hand Jack, Jack of All, Red Jack, Dealin' Jack, and Jack the Knave. Jack-in-irons and Jangling Jack are also names he's been observed to use. I've even heard speculation that the character from the Three Penny Opera was not originally named Macheath (AKA Mack the knife. Only one letter off you may notice.). And we can only speculate as to what sort of deal lead to Jack the Ripper (it could be coincidence, but the similarity in the name does point to the possibility. Perhaps it was not Jack who did the killing but the killer made a deal to avoid being caught). Now, we can't be suspicious of every Jack we meet, which brings us to another identifying feature . . .
His hand. Specifically his right hand. It may be mangled (allegedly from some accident), burned or scalded, red (from a birth mark, some disease, or in some reports as if it had been dyed), covered in a glove (usually red. I've never heard of a report of him having both hands gloved.), or replaced with a prosthetic device (while I've heard of him showing up with a prosthetic hand of various types I've never heard of it simply being gone. There would be nothing to shake at the close of the deal.). He may even attempt to keep his right hand out of sight until it's time to shake on the deal. It's always his right hand never in my experience the left. Those who shake his hand have reported that it seems somehow inhuman. Sometimes it feels almost hot enough to burn, others have said that something moved in a way a human hand should not, others yet found that his hand felt coated with slime or as if it was encased in a hard carapace.
Third there is his flask. How fancy the flask is depends on what sort of image he's trying to project. If he appears homeless then it's usually battered and old, although I've heard of him using a bottle in a brown paper bag as well. If he's trying to come off all high society it's probably going to be a lovely antique or something with beautiful engraving possibly made out of sterling silver. No matter how much he drinks the flask is always full. He has occasionally been known to offer people he's dealing with a sip from the flask. Those who take him up on the offer will find that what's inside will vary as much as the appearance of the container. Usually but not always the appearance of the flask will indicate the quality of the liquor inside. Rotgut whiskey or vodka in a brown paper sack, or high class cognac in a silver and cut crystal antique for example. Whatever the contents are they are inevitably described as extremely bitter. Some speculate that the contents are infused with wormwood.
I wish I could provide you with more details but they vary from tale to tale. He's black/white, short/tall, musclebound/emaciated, bald/long haired . . . you get the picture. Aside from his hand and his flask he looks the way someone who is where you find him should look. Theoretically he could show up at a white pride rally to make a deal with one of those assholes and then five minutes later make a deal with someone from the Nation of Islam without anyone in either location thinking he's someone who doesn't belong.
No one knows for sure what he is but it's widely thought that he is not one of the Fears but something else entirely. Certainly he blends with humanity better than many of Them and there have been reports of beings making deals with mortals for a very long time. All I know for sure that once you've identified him there's only one way to protect yourself. DON'T MAKE THE DEAL. Do not even say anything that could be remotely interpreted as accepting the deal. Do not shake his hand or drink from his flask as these are also widely accepted signals that one has accepted a bargain proposed to them. Refuse his bargain and leave. I've never heard of him preventing anyone from leaving before, he usually seems to feel you'll be back eventually. There is a first time for everything though so be careful.