Dan has an English degreeHe knows his Shakespeare very well. He has a habit of correcting people's grammar. Plus he doesn't seem to have a job.
Dan is part NeanderthalNote his sharp teeth, short stature and aversion to vegetables. Neanderthals were almost exclusively carnivores, and their short stature was a result of adaptation to cold climates. This also explains his rather pale skin.
At one point, Dan will try to get revenge on an entire continent.And of course, it would be for an INCREDIBLY dumb reason.
Dan once worked as a school bus driver.This is what made him Madden Into Misanthropy. Alternatively...
Dan once worked for the United States Postal Service.You don't see it?
Dan lives a sad and pathetic life.He lives in a miserable hotel. He gets his best friend to help, but he is already married. It sucks to be Dan, and so he takes his anger out on everything else.
Elise was the one who smashed in the window of Dan's car in "New Mexico."After learning of Dan's quests for revenge, she framed New Mexico for messing with Dan's car, knowing he would want to take a trip down there. That way she could just "tag along," and get her revenge without seeming as crazy as Dan.
Dan is Karkat.He's short, angry all the time, and always yelling.
Dan isn't gay, or is at least bisexualWhy? Because it'd be a funny subversion where the seemingly gay friend isn't completely in the closet and just hasn't had much luck with women at the moment.
Dan isn't gay, but he thinks that Chris secretly is.His having Chris say he loves him wasn't wishful thinking. He honestly thought that's the kind of thing Chris would have said and wanted his impression to be as accurate as possible. That's why Dan's own response was awkward and uncomfortable.
Ted will be the Big Bad of either the series finale or the season 1 finale.
Dan is somewhere on the Membrane family tree.Dib and Professor Membrane inherited his hair color, while Gaz inherited his attitude, temper, and...volume level.
Alternatively, Dan's descendants will marry Chris's descendants and they'll be the ancestors of the Membranes.All of the Membranes have intelligence not unlike Elise (even Gaz is amazingly adept at technological things) and Gaz and Elise have the same hair color. In addition to that, Gaz also has some of Dan's traits, as noted in the previous guess. Granted, given how unlikely it is that he would get close to anyone other than Chris, it might actually be the descendants of Dan's relatives rather than of Dan himself.
Dan is related to EliseThis is implied in the episode "Family Thanksgiving." Elise's mother wants Dan's special deviled egg recipe because they taste just like the ones her mother used to make, before taking the recipe to her grave. Dan later says that he "stole the recipe from (his) grandmother on her deathbed." Draw your own conclusions.
One of Dan's descendants (or relatives' descendants) goes on to found the Angry Marines.Dan's always angry. ALL THE TIME. One would assume it runs in the family.
Dan has some sort of mental disorder.In "George Washington," Elise remarks that hanging out with Dan is like hanging out with a big kid. Also, Dan doesn't seem to have a job, or any friends outside of Chris. This seems to hint at a disorder, some form of autism, maybe.
At some point, Elise will invent a machine that will enable Mr. Mumbles to talk...and he'll be voiced by Bill Kopp.Hey, the guy's already involved with the show, and it's not like he's never played a cartoon cat before.
Dan's last name is Kataiser.They look similar, and Dan would have reason to be paranoid at everything after nearly dying at least twice. They just managed to rebuild civilisation really quickly by the time he got older.
Ted is Dan's Freudian Excuse.Ted committed a crime. Dan knows it and testified against him, but Ted got off due to lack of evidence. The crime was was so evil and so horrible that the fact that he got away with it made Dan bitter and disillusioned with the legal system (and eventually all aspects of society), thus making him into the man he is today. This is also why Ted is on his list. Nobody other than Dan even believes that Ted is guilty, thus making their comments about him emotionally low key. If Ted ever actually shows up, he'll be a jarring Knight of Cerebus in a similar vein to The Lich on Adventure Time.
Dan and the Hills are somehow related.In the episode, Master of Puppets, Bobby did the exact same kind of skyward scream ("Date Niiiight!!!"). Another similarity: Bobby is Camp Straight while Dan is Ambiguously Gay. And you could argue that he has Cotton's temper.
Ted is the one who chopped the tree down in the Vs Washington episode.He may be stalking Dan, and personally setting up several of the more unexplainable instances that have occured.
Ted is DanNot Dan Dan, Imposter Dan. Dan knew that Ted was an identity thief, but decided to keep his enemies close. Of course, this is Dan, so Ted eventually got far enough away that he could come back. Alternate MG: Ted was a girl.]] Not just any girl, but Dan's first girlfriend. This little tale takes place before Dan was the Dan we know today, even before he knew Chris. This takes place in highschool. Teddy and Dan were juniors (That's important later) and had been going out for since mid-sophomore year. Just before the end of junior year, Teddy broke up with Dan and started going out with one of Dan's friends. Dan had to watch them all of senior year, and grew very cold. His other friends left him, seeing what he was becoming, and Dan went on alone. Dan met Chris in college, and, when asked about his other friends, said that he had a friend named Ted. Chris never met Teddy or as we know him, Ted. Dan has always had Ted on his revenge list, In fact, Ted was the first name on the list. Dan will eventually take his vengeance on the girl that scorned him, but that episode won't happen for a very long time.
Dan is the reincarnation of Napoleon BonaparteHe is short and angry at the world for no particular reason. All he needs is a Cap'n Crunch hat and he's set.
Dan is part Native American.The reason he is able to afford his rent and food is because the money gets for being a registered part of the tribe.
Dan and Elise are cousins.Think about it. Elise's mom said Dan's deviled eggs taste like her mother's and that she's dead. Dan got the recipe from his grandma on her death bed. I don't think either of their families is close knit, so it makes sense.
Dan is/was Skipper Dan.He's clearly familiar with Shakespeare, and his anger towards the world could easily be caused by one too many soul-crushing days as a tour guide on the Jungle Cruise ride, adrift on a (possibly artificial) lake with nothing but annoying tourists and his own crushed dreams.
Dan is secretly an English teacher.As mentioned above, Dan does have an English degree, and he does get money from an ATM in "The Bank", so maybe he picked up some sort of job without telling anybody, possibly due to paranoia. He could just be constantly fired due to anger issues, but somehow keeps finding a job, which explains why he'll be broke one minute ("I want my money back!" "That was MY money."), and be able to afford an apartment, cat food, etc.
Chris will completely snap in a future episodeAnd it won't be pretty. AT ALL.
Elise will get A Day in the LimelightShe'll need to get revenge on someone/something as part of a mission, and enlist Dan's help.
Hortense will reappearThe episode will be a non-stop Heartwarming Moment.
Dan's parents will appear and they will be evilThey will be a Knight of Cerebus and bring about the darkest episode in the series.
Dan is Squee CasilTo begin with, this could easily be the same universe as Johnny the Homicidal Maniac. The wolfman exists, every bizarre conspiracy is real, and rule of funny is a law of nature. Besides, both series take place in the same geographic area. The way I figure it, Squee grew up nasty and prone to lashing out at random people/things partly because of Nny’s influence, and partly because of snapping under the stress of being born a karmic punching bag. He’s short because his parents never fed him properly, and the horrific childhood that scarred that therapist was Squee’s normal life. He shies away from killing, though, because who wants to be too much like as horrifyingly (if amusingly) miserable as Nny? I can’t explain the name change—might be a nickname from college, might be the result of a hilarious anecdote involving the legal system.
Dan will end up with HortenseEverything he said about Jeremiah Burger at the end will come true.
Everyone that Dan faced will do a Villain Team-Up against Dan.Extra points if Dan doesn't remember and/or they yell DAAAAAAAAAANNNNNNNN!!!!!!!!!
Dan was once a librarian.Re-watching the episode "Dan Vs. Mall Santa" his resume also lists "Library services".
Dan's name was inspired by Danny Greene.Danny Greene was an Irish mobster who lived in Cleveland who had a particular skill at explosives and attaching them to cars. With Dan's affection toward his car and one of his first things to use for ventures in revenge being explosives, its an interesting theory on how the creators of the show choose the name.
Imposter Dan will only appear in one episode each season.And each would be getting revenge on Dan in various ways. Jossed for season three.
Dan used to be a psychiatrist.After hearing so many of of people's problems, he decided he hates everything and everyone.
Dan constantly ropes Chris into these plots to get Elise to divorce him.But not so he can be with Chris. It's actually Elise that he's after.
For once, Dan will go under a Tranquil Fury in his revenge.It shows deep down, Dan really does care for Chris, and to Elise to an lesser extent.Perhaps, when the two gets in danger, and instead of exploding. Dan simply gets his head in the gear.
The series finale will have Dan vow revenge on humanity as a whole.It could end in either a Heartwarming Moment or a Tear Jerker.
Elise knew Dr. Pullem was a Super Villain.It's been shown a few times that Elise works for some shadowy government spy outfit. It's entirely plausible that this organization had developed a dossier on Dr. Pullem, but didn't have the evidence to move against him. Elise, seeing that Dr. Pullem was Dan's dentist, and that Dan had a convenient grudge against him, lied about Pullem drilling a new cavity in Dan's mouth. This gave Dan the fuel he needed to really get after Pullem, and take down his supervillainy. A little bit of Magnificent Bastardry, and Elise kills two birds with one stone; helps Dan get his revenge, and puts an indirect stop to Pullem's schemes.
Ted is Dan's son.Because of that actor from Cheers.
Dan met Chris through Elise.Not actually my idea, but I read this somewhere and thought it was interesting. Dan was close to Elise prior to meeting Chris, and is bitter at her for marrying him since he views marriage as a "commodity". He attempted to stop the wedding, but wound up becoming best friends with Chris through all the shenanigans. This explains why Dan and Elise have so much tension, and yet at the same time Elise is more tolerant (and occasionally affectionate) of him then someone else who doesn't have a history with him.
Dan is Jacknife or related to him.They both have misanthropic qualities, they both aren't above committing felonies, they have a nearly IDENTICAL growl, they even look similar!
Dan was stalked by Slender Man as a child, and he may still be hanging around, we as people he isn't stalking just can't see him.It would certainly explain his paranoia, anger, and just general distrust of every little thing in his life. Except for Chris, the people being stalked by the Slender Man always have one close buddy, in some way. And why he was so against getting a pet until he actually saw Mr. Mumbles. And is so protective of her. What with Slender Man leaving dead animals, even pets, for his victims to find.
Dan is Grunkle Stan's SonThey both do Skyward Screams. And Grunkle Stan evidently thinks that "Avenge Me, Kids" is an okay direction for a child. Also, they seem to have similar disregards for the law, and growing up in Gravity Falls would go pretty far towards explaining Dan's conspiratorial World view.
Dan is a representation of Chris' repressed anger.Chris always lets people walk all over him. Dan was created years ago as a way of venting his frustrations. Dan does what Chris wishes he could do. Or, they will do an episode where Chris accidentally ends up in a mental institution where the doctors think Dan is made up.
The Imposter was put into the witness protection program when he was very young.And ever since then, he didn't know who he is truly was; It felt like most of his life was a lie. So in an attempt to try to be happy, he became an identity thief, so he could find a life that worked for him and who he wanted to be.
The Imposter is the one who hired all of Dan's other enemies to torment him, and is secretly the Big Bad of the show.Considering that the Imposter is Dan's possibly most hated enemy.
Elise's employers need Dan.The only reason Elise put's up with Dan is because his cockamamy revenge schemes to take down major criminals or prevent major diasters from time to time. Elise is there to provoke Dan into chasing certain bad guys, or to keep him from causing periphery damage, but more or less Dan is super-valuable to the quasi-government agency because he does their job without pay.