I'm going to talk about two things that don't have to be related, but often are: fetishes and worldbuilding.
Fetishes are obsessions that are almost always sexual in nature, but don't necessarily have to be. Many webcomics out there could be categorized as fetish comics - not necessarily porn comics, but comics in which the authour's obvious fascination with some topic or other tends to dominate the narrative. I've seen fetish comics about growing and shrinking, fetish comics about people swallowing each other whole, fetish comics about getting fat, fetish comics about BDSM... given its attention to anatomical detail, I'd even categorize Moon Over June as a gynecology fetish comic, rather than just a porn comic for an audience attracted to women.
The key difference between a fetish comic and a comic that just happens to feature a great deal of some element is the degree to which that element defines both the plots and the characters. Leftover Soup, for example, features quite a lot of boardgames, but I highly doubt anyone would categorize it as a boardgame fetish comic. Many characters don't play the games, and the characters that do will generally just play, finish, and get on with their lives. Leftover Soup would be a boardgame fetish comic if almost every plotline was, in some way, related to tabletop gaming, and characters constantly talked about gaming any time they weren't actively playing. It would be a boardgame fetish comic if nine characters out of a cast of ten were all game fanatics, and a major plot arc was about trying (and, inevitably, succeeding) to find the game that would allow the tenth character to join in their obsession.
(I suppose one could make the argument that Leftover Soup is a fetish comic, if one counts amateur philosophy as a fetish, but that's a bit of a stretch...)
By far, by far, the most common fetish for webcomics is transformation.
I could name off quite a few transformation fetish webcomics - some pornographic, some not. Some start their first plotline with their protagonist going through a transformation, then spending the rest of the comic dealing with their new form. Others have new and different transformations every few pages, often as the initial catalyst of a plotline, often functioning as the plotline in its entirety. In either case, characters often transform rapidly and unexpectedly, they often bust out of their clothing, and they often have to take time to get used to the features of their newfound anatomy... sometimes sexually, sometimes not.
And, unless the rapid, unexpected transformation in question is a car-accident-induced amputation, that means you're dealing with either some sort of magic or science so advanced that it might as well be magic, which brings me to my second topic.
All comics have to have a setting. Very often, almost all of that setting can be implied, especially if the comic is set in the quote-unquote "real world". If you're using magic or hypertechnology to drive your plots, however, it's important to define how that magic or that hypertechnology works.
Very often in subpar fantasy fiction, the nature of magic is left vague and unspecified. In a way, this can provide an authour with enormous freedom - simply have your protagonist whip out whatever improvised magic power is required to get them from point A to point B in the plot. This freedom, however, comes with a cost - if your readers have no sense of exactly how things work and why, your plot points will feel cheap and there will be no sense of urgency to any given crisis. If your protagonist is facing down a horde of clockwork monsters, and after a tense chase scene just so happens to have a heretofore unmentioned anti-clockwork spell that solves all their problems, then your audience will feel - quite rightly - that the danger was never real, that actions have no consequences, that events are arbitrary, and that the entire story is more akin to a nonsensical dream than an adventure.
This is where worldbuilding comes in.
Good fantasy authours need two skills when it comes to worldbuilding - they have to be able to co-ordinate a lot of information, and they have to be able to impart that information as painlessly as possible. Without the first skill, your world is incoherent, inconsistent, and confusing. Without the second, you're forcing your readers to plod through a phonebook. The best worldbuilders will have an entire encyclopedia at hand - a whole universe's geography, history, physics, and society - and can transmit that fullness from their head to yours without sacrificing the story or making it dry - they show, rather than tell.
Which, at last, brings me to our webcomic for today, one of the best examples of the worldbuilding skill I have ever seen:
The Dragon Doctors is, in theory, a fantasy adventure comic about a team of four magically skilled physicians, but in a much more important way, it's a comic about a world.
Specifically, it's a comic about our world, many centuries after magic was re-introduced and after a few apocalyptic events broke it and put it back together. It's a world in which curses and spells and hauntings are commonplace. It's a world populated with dryads and beastmen and wizards and aesthetically-pleasing humanoid arrangements of crystaline structures.
And, of course, it's a world in which people get transformed into things left, right, and center.
In fact, the very first chapter of the story involves all four of the titular doctors unexpectedly, instantly, and irrevocably switching their genders.
Yeah, like I said - fetish comic.
But, as I also said, "fetish" doesn't necessarily mean sex. Dragon Doctors is absolutely not a porn comic, and anyone headed there hoping for explicitly-depicted scenes of tentacle-on-catgirl hanky-panky is going to be sorely disappointed. It is, however, a comic about adults, for adults, and sometimes those adults are going to fall in love with each other and express it - offpanel - physically. In addition, there's plenty of action, usually in the form of magical battles of some sort, and occasionally magic can not only result in graphic violence, but also incidental nudity.
Dragon Doctors is one of those rare cases in which the phrase "adult content" is apt. Too often, "adults only" simply means "boobs and gore, don't let kids see this". Dragon Doctors, however, features "adult content" in the sense that plotlines and story elements are geared towards an adult audience, and reward adult-level attention and contemplation.
If DD has a theme (in addition to a fetish), it would be human rights... or, rather, in a world filled with non-human citizens, personal rights. Characters frequently use the term "violator" as a catchall declaration of wrongdoing. In a world so full of magic (particularly transformative magic), "violation" can cover anything from forcibly turning someone into a tree, to instilling a compulsion, to garden-variety domestic abuse or sexual assault.
It's worth noting that the main characters are doctors, and the vast majority of their plotlines revolve around assisting - by any means necessary - people who come to them for help. Other major characters are politicians and police officers, and a major organization in this world - The Hearts Society - is devoted to helping people who have, somehow, been victims of violation... think Amnesty International, if Amnesty International had actual governmental authority and was staffed with high-powered sorcerors.
I find it interesting that much of Dragon Doctors is concerned with good versus evil - doctors who heal and help versus monsters who torture and kill - but "good" and "evil" themselves are not elemental as they would be in other magical worlds. There are no angels of perfect light or moustache-twirling villains who do evil for evil's sake - bad guys are people who can be motivated by greed or anger or cruelty or self-preservation. As such, I think the violators of DD are excellent metaphors and parallels to the real world's less supernatural equivalents, and serve as an excellent springboard for talking about abuse and pain and loss and how to deal with them.
I think our pop culture would benefit from a few more heroes that are explicitly dedicated to rescue and healing. I'd like to see more movies or comics or novels in which protagonists are badass not in spite of the Hippocratic Oath, but because of it.
"The Doctor" doesn't count, he's a prat with a magic wand and a horseshoe up his ass and I wouldn't trust him to lance a pimple.
aaaaand by now, you've noticed Dragon Doctors' art. Or, rather, the lack thereof.
I've often said that if you want to teach yourself to draw, starting a webcomic is one of the best ways to do it. Certainly, the art in Dragon Doctors has improved over the years... sort of.
You see, the thing is that Speedball (Dragon Doctors' writer and artist) has a tendency to fall behind on his update schedule... and when he does, he either posts fanart he's received, frantic apologies to the audience, or base sketch comics - some of which he goes back and finishes, some of which he doesn't.
A lot of what goes on in DD would be artistically challenging to anyone, and I have a lot of respect for Speedball for sticking with it, but I couldn't help but feel that he'd benefit from building up a buffer so he isn't constantly running on fumes... and from a figure drawing lesson or two.
So, do I recommend Dragon Doctors?
Well, if you're the sort of person who reads comics for the exquisitely detailed landscapes - or the exquisitely detailed tentacle-on-catgirl hanky-panky - then no, no I don't. But if you're the sort of person who reads comics for the action and adventure, if you're the sort of person who reads comics for the sappy love stories, if you're the sort of person who reads comics for commentary on abuse and trauma and healing and growth, if you're the sort of person who reads comics to be transported to a magical world... then yes. Yes, I do recommend it wholeheartedly and unreservedly.
The Dragon Doctors has been updating a couple of times a week for years now, if you're going on an archive binge - which is the ideal way to consume it - expect it to take a few hours. Start from the beginning.