Here be spoilers, although I've tried to keep you away from major plot developments. Which, to be honest, I seem to be really bad at. Read at your own risk.
Dollhouse came onto the air in February of 2009 with crazy-high expectations. Creator and showrunner Joss Whedon had built a reputation and a cultish fan following with the landmark Buffy the Vampire Slayer (and its spinoff, Angel) and added to it with the too-beautiful-to-live Firefly (and its movie follow-up Serenity). Buffy regular Eliza Dushku was slated to star, alongside some newcomers and Helo from Battlestar Galactica. Whedon had sworn never to work with FOX again after its legendary mishandling and subsequent cancellation of Firefly, but he had agreed to do this. Fans waited with baited breath, and some even started a "Save Dollhouse" campaign before the show ever premiered…just in case.
The premise was as high-concept as a network show could probably be. The title referred to a business, run by the probably-nefarious Rossum Corporation, that essentially rented out people. But rather than actors, these "Actives" were mind-wiped clean slates, programmed to be who or whatever a client required. Their minds were supposed to be wiped clean again following these "engagements," rendering them helpless, mostly-mindless "Dolls" in the Dollhouse. (The Dolls were allegedly volunteers that had agreed to a five-year service in exchange for supposedly waking up with their personal issues sorted and their bank accounts much enlarged.) The conflicts that would power the series was one Doll's slow journey into self-awareness, certain Dollhouse employees ethical issues with the whole enterprise, and the combined threats of Rossum and the mysterious Alpha. It sounded like an exploration of the more dark and disturbing themes alluded to in Whedon's other series--the extremes of "programming" people from Firefly, the "chosen" ass-kicking girl from Buffy, the inadequacy of a right/wrong binary in Angel, and the hefty distrust of authority and institutions in all of the above. (And the Dolls' names were taken from the NATO phonetic alphabet, which was just cool.)
And then the show premiered, and fans scratched their collective head. It was…not as expected. Where was the snappy dialogue, with its pop culture references and/or Chinese slang? Why were we so unsure about rooting for the Joss-insert character, when we'd adored Xander and Wash before him from the get-go? In fact, who were we supposed to root for--the morally questionable Dollhouse employees? The Dolls, who we felt kind of bad for but who were quite literally not characters? The lone-gun FBI agent trying to root them out? The new Dollhouse handler who gave the whole operation a sidelong glance but showed up at work anyway?
As the first half-dozen episodes of the season aired, we continued to wonder. Episode after episode showed the many facets of the premise--Echo played an expert safecracker, a pop star's backup dancer-slash-bodyguard, a blind cult follower, and several variations on a fun-loving gal who just wanted to ride motorcycles and have sex (it was Eliza Dushku and FOX, after all). Other Dolls, mostly Victor and Sierra, played supporting roles in Echo's adventures, and Agent Ballard of the FBI chased a ghost of a lead on an urban legend. Adelle, the Los Angeles Dollhouse location's manager, was cool and crisply British; Echo's handler Boyd continued to be conflicted but caring; and programmer Topher continued to make us miss his morally uncompromised predecessors. Dushku also lacked the acting chops to play the multitude of characters Echo became, which became even more readily apparent next to the talents of the actors playing other Dolls.
But Joss & co. kept saying to stick it out through "Man on the Street," so we did. And everyone watching--mostly if not all dedicated Whedonites--started to realize, "Oh, that's what it's about." But the rest of the season progressed with similar unevenness--we'd be wowed by the revelations in "A Spy in the House of Love" and captivated by the suspense of "Briar Rose," only to be let down by one-off episodes centered around Echo, who still didn't seem all that self-aware. By the time the twelfth episode, "Omega," aired, there was a widespread assumption that FOX would axe the series--the network didn't even air the season's proper finale, "Epitaph One."
But not only did FOX renew the series, the unaired "Epitaph One" was released in iTunes in the summer of 2009. Taking place ten years later than the rest of the series so far, the episode explored the most dangerous consequences of the Dollhouse technology. The new story plunged into a very different world, was told half in flashbacks, and minimized use of the main cast. And it was more intriguing than almost everything leading up to it.
The second season got off to a start as rickety as the first, and it had its share of low points--in one episode, Echo played a nursing mother--but now we understood the endgame. And as soon as FOX did cancel the series, every episode started to turn the dial to 11. See, unlike with Firefly, FOX canceled Dollhouse but kept its 13-episode order--meaning that the show could wrap up at least mostly onits own terms. The story sped up, dispensed with the one-off Echo episodes, and started to move toward the future that we saw in "Epitaph One." Alliances were forged, allegiances were revealed, and Summer Glau showed up with a dead arm. By the series finale, appropriately titled "Epitaph Two," were were left with more loose ends and unexplained twists than most of us would've liked, but things had come to a largely satisfying (if convenient) conclusion.
(Many of the characters in Dollhouse answer to a multitude of names, so I'm doing my best here. Usually, a Doll name is used to refer to a Doll in tabula rasa state or in a composite state, with their given name referring to their original self, which can sometimes pop up in someone else's body. When properly imprinted, a Doll is that person, so Echo technically refers to someone distinct from Caroline Farrell, who is also someone distinct from the various personae assigned to Echo--even though they're all realized through Eliza Dushku's body.)
Echo (Eliza Dushku)
Originally a radical activist called Caroline Farrell, Echo is unique among Dolls in that she can hold multiple personality imprints in her mind and seems unable to be wiped fully clean. It's never clear why she has this ability (though it's implied to be biological), but as a result of it, Echo retains the memories, knowledge, and skills of her past engagements, which she uses to try to free her fellow Dolls from the Dollhouse and later the far reaches of Rossum. Echo is ultimately a composite, governed by pieces of Caroline into operating as a functional individual. She was contracted to the Dollhouse as a way to avoid prosecution for breaking into Rossum's labs, and many of her engagements involve sex, ass-kicking badassery, or both. (Faith would be proud.)
Adelle DeWitt (Olivia Williams)
The Dollhouse's director and later a defacto leader of our odd band of heroes, Adelle cares deeply for the Dolls in her house, though it's not always clear whether she considers them people or commodities. She walks a fine line between good and evil and mostly operates in a gray area. Adelle is cool, often ruthless, and British to a fault, and she subtly looks out for Topher. The details of her personal life are mostly left unmentioned, but when they start to bleed into canon, she becomes one of the most interested characters on the show.
Topher Brink (Fran Kranz)
Topher is the Dollhouse's lead programmer, a young and certified genius who singlehandedly revolutionizes the Dollhouse's technology over and over. His initial involvement in strictly amoral--as Adelle says, "You always take good care of your toys." He's interested in exploring the reaches of his own genius, geeking out over most of the things that Xander Harris would have more, and his drawer of inappropriate starches than money or world domination. As his genius starts to outstrip his and Adelle's ability to control its consequences, he starts to fall apart.
Paul Ballard (Tahmoh Penikett)
Paul begins Dollhouse as an FBI agent trying to track down the Dollhouse, an urban legend, which ends up costing him his career and most of his sanity to boot. He is determined to find Caroline Farrell--even after meeting Echo--and convinced that the Dollhouse is inherently wrong, even as he gets roped into its machinations.
Victor (Enver Gjokaj)
Once a veteran of the War on Terror in Afghanistan named Anthony Ceccoli, Victor joined the Dollhouse voluntarily to escape his PTSD and is at one point even released according to the terms of his contract. His engagements are fairly varied, but Victor is more interesting because of who he is when wiped clean--which is to say, blank, but inexplicably and utterly drawn to Sierra, to the point that their mutual magnetism begins to bleed into their imprints. As a soldier, Victor ends up another defacto leader of the group, but he comes to see the tech as more of a tool rather than a force of good or evil.
Sierra (Dichen Lachman)
Sierra's reason for being in the Dollhouse is more horrifying than most--a wealthy Rossum investor was obsessed with her from her days as a sidewalk artist named Priya Tsetsang and had her committed when she refused his advances. Though she has plenty of other engagements, often in conjunction with Echo's, Sierra is frequently contracted to her captor imprinted with variations of her actual self that return his feelings (such as they are). Meanwhile, she develops an attraction to Victor in their respective Doll states (meaning they mostly stand around and smile at each other--Dolls aren't capable of much more) and a similar if platonic friendship with Echo. As the plot thickens, Sierra regains her original self and (understandably) becomes opposed to the Dollhouse tech in any form, which is a source of conflict with Victor.
Boyd Langton (Harry Lennix)
We meet Boyd on his first day as an employee of Adelle's Dollhouse when he becomes Echo's handler. Though he seems dubious about the morality of the Dollhouse, he is fiercely protective of Echo, to the point that he tries to turn down Adelle's promotion to her head of security. Despite their obvious shared feelings about Echo and the Dollhouse, he and Paul don't quite see eye-to-eye, but he forms a connection with Claire Saunders, the Dollhouse's in-house physician.
Laurence Dominic (Reed Diamond)
Adelle's original head of security and a government plant in the organization, Dominic has a major if unspecified beef with Echo, to the point that he tries to kill her. After his double-crossing is uncovered, he ends up in the mysterious "Attic" with other "broken" Dolls, though he reappears later on as a force…if not for good, than at least on the same side as most of the rest of the cast. His main interactions are with Adelle (they share a delightfully dry and crackling rapport), and she briefly resurrects him as an imprint in Victor's body.
Claire Saunders (Amy Acker)
The Dollhouse's doctor is quiet, perennially sad, and just a little bitter toward the pretty Dolls she cares for, with their perfect bodies and faces, whereas her face is crisscrossed with scars from the attack by Alpha that precedes the beginning of the show. More is revealed about her toward the end of the first season and into the second, and she ends up playing pivotal roles both in "Epitaph One" and in helping Boyd.
Mellie (Miracle Laurie)
Paul's neighbor and confidant, Mellie's a bit of a one-note character--she mostly makes him lasagna and maintains an unrequited crush--until "Man on the Street," when she turns out to have a bit more going on. Paul eventually returns her advances though his interest is really in Caroline/Echo. By the time we reach the "Epitaphs" stage, she is a warning to others, but not quite in the way you would have anticipated.
Ivy (Liza Lapira)
Topher's assistant is almost as brilliant as he is, and puts up with fetching him juice boxes to boot. Toward the end of the series, Topher sends her away with the admonition not to become like him, but Ivy ends up being instrumental in the continuity of the comics that span the timeline between the bulk of the series and the "Epitaphs" episodes.
Alpha (Alan Tudyk)
Alpha is the Big Bad of Season 1, and a shifting target in Season 2. We're introduced to him by name only and eventually learn that he killed Echo's previous handler, a number of Dolls and Dollhouse employees, and slashed up Saunders's face. His obsession with Echo is revealed in the season finale: he recognizes their shared ability to hold multiple imprints and become a composite of them, but unlike her, his effective multiple personalities have driven him extra-crazy. His machinations end up being far less destructive than the Rossum Corporation's, though, and he becomes a bit of an ally.
Bennett Halverson (Summer Glau)
Topher's counterpart at the Dollhouse's Washington, D.C. location, Bennett shares a history with Caroline Farrell and Rossum (which leads her to torture Echo) and a shy mutual attraction with Topher. Her dead arm ties into the former, and the latter, unfortunately, turns into one of those plot developments that Joss Whedon is famous for. Bennett is shown to be shy, but highly capable and confident in her work; her programming of Daniel Perrin impresses Topher, and he later turns to her to help resurrect the damaged hard drive that contains Caroline Farrell.
THE FANDOM AND THE FIC
Most of the Dollhouse fandom is a subset of the larger Whedonverse fandom (which is technically three distinct fictional universes, but there's heavy overlap of fans and a fair amount of crossover fics, my favorite of which is linked below). Unlike the Buffyverse and the Firefly 'verse, though, which are as wide-ranging in subjects and pairings as the day is long, Dollhouse fics tend to fall into one of three categories. Most popular are stories dealing with the lead-up to and the aftermath of the "Epitaphs" stories, which have many of the hallmarks of awesome post-apocalyptic stories. A number of fics also play with the potential of the tech in more fun and cracky ways (for instance, there's one fic where Sierra is imprinted to become an Ewok). And there are a fair amount of character studies beyond that.
Crossovers with Dollhouse usually involve bringing characters into the Dollhouse world (certainly that's what I did) or incorporating the same tech into a different setting. All-out AUs are rare in this fandom, as the characters are so tied to their circumstances and the tech that it's hard to transport them to, say, high school or a coffee shop.
Pairings mostly adhere to canon (again, in contrast to most of the rest of the Whedonverse). Sierra/Victor (or Priya/Victor) and DeWitt/Dominic are the most common. Echo is usually paired with Paul or Alpha, with some rare forays into femmeslash with Sierra and Bennett cropping up. Saunders/Topher, DeWitt/Topher, Mellie/Paul, Bennett/Topher, Saunders/Boyd, and Echo/Boyd are all out there, too. And a client engagement, of course, can lead an Active to be paired with just about anyone.
For more fic, check out Dollhouse-specific communities like dollhousefics and victor_sierra or Whedonverse communities like joss100 and whedonfanworks, or the always-reliable AO3. And there are of course plenty of excellent recs at the Dollhouse tag in this fine community!
Fic Rec #1: Identity Crisis
Why This Must Be Read: Sierra's 32 personalities and Victor's 49 personalities composite and go on the run together. A quick, clever, spot-on-in-character look at what might happen if Sierra and Victor ended up as multiple-people-in-one-body the way Alpha and Echo did. Slightly AU, as that didn't (and then, it turned out, couldn't) happen in canon.
Fic Rec #2 Composition
Pairing: Priya Tsetsang/Anthony Ceccoli (Sierra/Victor)
Why This Must Be Read: Priya's identity as an artist recurs throughout the series--in her dealings with Nolan and Hearn, in particular. This "five things" fic explores different ways Priya and Tony might have met, under different circumstances, through different mediums. It's all framed by Priya's realtime experiences raising their son in the "Epitaphs" world, which keeps the dreamscape firmly and harshly grounded in reality, even as it offers a little hope.
Fic Rec #3: Lines
Why This Must Be Read: dollsome is one of those authors who always seems to have written the best things for whatever new fandom I land in, and "Lines" is no exception. It explores Sierra as a Doll and an artist at heart--whatever that means for a person who isn't really a person--and how she comforts a scarred and scared Victor. This fic also does a particularly good job of showing the Dolls in their tabula rasa state, and to what extent they remain human even in that.
Fic Rec #4: Guns and Pretty Girls and Other Things That Steal Your Soul
Pairing: Priya Tsetsang/Anthony Ceccoli (Sierra/Victor)
Why This Must Be Read: Given how little we really know about Priya and Tony as people independent of the Dollhouse, this fic feels so rightly in-character it's amazing. The author weaves in the language of art (hers) and war (his) in the process of telling their story (from Tony's POV), from breakup (as implied in Epitaph One) to after they escape the "thoughtpocalypic" Los Angeles. It's more or less consistent with canon. I've come back and re-read this fic a few times. There's one line in particular that sticks with me every time: “I wish I could paint them,” Priya says, and his idea of happiness becomes a world in which Priya can paint again.
Fic Rec #5: Whatever Remains, However Improbable
Why This Must Be Read: Victor and Sierra are imprinted as Holmes and Watson, and awesomeness ensues, both of the mystery-solving and of the sexytimes varieties. My experience with the world of Sherlock Holmes isn't as extensive as it should be, but near as I can tell the author nails both of Sir Arthur's characters, and integrates them seamlessly into the Dollverse. I have a soft spot for Dollhouse fics about imprints of fiction characters, and this is one of the best.
Fic Rec #6: wrap my arms around him & pretend
Pairing: Adelle DeWitt/Victor
Why This Must Be Read: A short but painful look at a "Miss Lonelyhearts" engagement--dollsome makes you understand just why someone might want to engage the Dollhouse's services, even knowing it's not real.
Fic Rec #7: Never Even Scratched the Surface
Pairing: Adelle DeWitt/Victor
Why This Must Be Read: One of the creepiest parts about being associated with the Dollhouse--as exemplified by several characters--is never being able to fully trust your own self and memories. This is a short but eerily effective elaboration on that, and it takes a different direction than we see in canon.
Fic Rec #8: In The Time That We Have
Pairing: Adelle DeWitt/Laurence Dominic
Why This Must Be Read: In this short but effective fic, dollsome reunites DeWitt and Dominic, resulting in a conversation fraught with feeling that exposes the ways this fan-favorite pair have and haven't changed in the wake of the Thoughtpocalypse. There's also a cheeky bit about tea.
Fic Rec #9: Band-aid on a Bullet Wound
Pairing: Adelle DeWitt/Laurence Dominic
Why This Must Be Read: Dominic escapes the Dollhouse in Victor's body. Not only does this bring to mind Enver Gjokaj's uncanny Reed Diamond impression, but it also gives insight into what it might be like to spend time in a body you actively know isn't yours. Though the pairing here is definitely DeWitt/Dominic, there's a solid rapport between Dominic and Echo that's worth reading all on its own.
Fic Rec #10: Afterlife
Pairing: Echo/Paul Ballard, Echo/Alpha
Why This Must Be Read: After the events of "Epitaph Two," Echo and Alpha both have complicated self-exploration to do. For her, it's managing the memory of Paul alongside literally having him in her head. For him, it's navigating the return to his original self without unleashing a serial killer on the world. They don't actually interact in this story--it's really two separate threads--but damn if they don't have a lot in common.
Fic Rec #11: A Girl to Hold Onto
Pairing: Mellie/Paul Ballard
Why This Must Be Read: A short, quiet look at Paul and Mellie's relationship at the beginning of the series. He may never really love her, but it's a good insight into why he tries.
Fic Rec #12: Shadow
Why This Must Be Read: Fics that attempt to bring parts of the Whedonverse together--especially Firefly and Buffy--are far from uncommon. But I'm pretty sure you haven't seen too many mergers of the Firefly 'verse with that of Dollhouse--especially one that slots familiar crew members into just the right roles and gives Mal and company a whole new level of aimin' to misbehave. The merged voices are spot-on, and while "Shadow" is an AU within the Firefly 'verse, it's entirely believable that the Dollhouse tech could have been developed there. It also plays up the two series' shared distrust of traditional authority and themes of trying to control people at the individual level.
Dearest mods, we're missing tags for several ships here: Echo/Alpha, Echo/Paul, Adelle/Victor, and Mellie/Paul