Spoiler Free:
Mare Internum is a SciFi webcomic by creator Der-Shing Helmer following the journey of Dr. Mike Fisher on what is supposed to be his last day on a Mars space station. Mike is a troubled man, and due to his increasingly erratic behavior he has been fired from his research position and is to be returned to Earth. On his last day, he decides to give a new recruit a tour of a giant crater, inside of which is an ancillary research station-- a journey that ends messily due to Mike's paranoia and an ill-timed cave in. Injured and alone, with strange martian lifeforms starting to grow on and in him, Mike must make his way back to the surface, only perhaps he isn't as alone as he initially thought. . .
Story-wise, this series is a slow burn. It's not nearly as decompressed as Vattu, but the artist loves her some grandiose Martian landscapes. The art is phenomenal. This is the same artist behind The Meek, and while she's made it clear that the Meek is her ongoing Magnum Opus, Mare Internum is her passion project, and one with a clearer end in sight. While the update schedule for both has been a little wonky in the past, the artist has gotten together a successful Patreon account and now updates more frequently, going from a sporadic one or two pages a month to an average of two pages a week, with the occasional burst of week-long daily updates.
More Detailed, Slightly Spoilery:
There aren't many characters in Mare Internum. At least, none that have lasted that long.
We have Mike's commanding officer and the handful of crewmen on the station. There's also Bex, who is the new recruit on board taking over Mike's vacancy. She's in charge of creating sustainable protein food sources-- mostly crickets. She's got two kids back home and a loving husband. She's also spoiler. This last fact is what tips Mike over the edge during his cavern freak out before the collapse, as he cannot fathom why spoiler.
The character Mike is a bit of an asshole, but he's got reason to be. The current-timeline of Mike being stuck in an underground Martian oceanic cavern is interspersed with flashbacks from Mike's childhood. We see his neglectful parents, his abusive uncle, and his teenage fallout of both of those things (never made explicitly clear, but he sees a shrink and most definitely has "issues"). On top of all that, there's also implied to be some underlying psychosis involved as Mike is convinced that his LEVi droid was trying to control his mind-- the loss of said LEVi being the final determining factor in his termination.
We haven't seen much specifically regarding Mike's mental issues. I don't mean we don't see them; he's paranoid as hell, and so far he's had reason to be. He's self-loathing and depressed, and the first page literally opens with him trying to hang himself. He's clearly traumatized. But we haven't gotten much information on what specifically went wrong between him and LEVi, and the creator has implied in the comments of the comic pages that Mike's uncle has done far worse to him than the glimpse we get in the flashbacks. So whether all of Mike's issues stem from the traumatic events of his childhood, or if there was already an underlying problem like schizophrenia boiling up, we don't know.
Of course, this is assuming everything that's happened is actually happening and not all in Mike's mind-- which is still a possibility.
Along the way, Mike meets a few "friends." Most of these friends have no canon name, just the nicknames people have given them in the comments. There's Thighfriend, which is a fungus-like being that has has attached itself to Mike's broken leg. It flaps when it's mad, it hides inside his leg when it's threatened, and it likes drinking water. What is it? Why is it there? That's explained later. There's also Thrip, a strange shrimp-like creature that isn't really acknowledged by Mike, but accepted the way someone accepts a disfiguring mole. The last Martian friend is nicknamed Armshark. It has a real name, but I'm calling it Armshark for now.
Armshark is apparently a native martian, and has an expansive memory going back to before the Earth was formed. Armshark remembers the formation of the Earth, the mass exodus of Martians, the Martian use of technology, and meeting Mike's LEVi. However, when Mike finds LEVi broken at the bottom of the Mare Internum, the titular Internal Sea, and Armshark has no memory of the incident, it realizes that perhaps it doesn't know as much as it thinks it does about the nature of life on Mars.
This comic is cool. Like I said, it's a slow burn, but it's a great one to leave for a couple months, then binge-read on. The author is pretty interactive with her readers-- going into the comments and talking to people, showing off rough sketches and doodly mini-comics, and making tutorials and process-videos for Patreon sponsors. If you like space, like troubled main characters, or like helpful little space shrimp, go read this comic.