Hi there, and welcome to the ET story bible.
This is an overview of writing Eternal Tails, particularly Miles Prower and his peculiar mental states. This was primarily written for my own convenience, but a very kind (and anonymous) reviewer asked me to put it up, so I did.
Any and all ET stuff or canon interpretations within are totally free for use, for ET stories or not (well, I'd prefer you not put Eternal Tails in the title unless you're actually writing an ET story about Miles or another character within the ET canon, but you know, you do you). While it is primarily oriented towards Miles' mental states and ways of dealing with the world, most of the content is based on canon observations and might offer a different perspective into Tails or the setting you can use for your own stories, and might be useful for writing other, mentally unstable characters suffering from past trauma.
While mostly notes, there are simple stories throughout the text that can be found by keeping an eye out for "Story:". I make no great claims as to their quality, but they serve as examples and to follow site rules that this shouldn't be exclusively a collection of author's notes. Why I have decided to have all of these examples be written as crossover with Old Yeller can be attributed to sleep deprivation on my part.
As might be expected, this spoils a lot of the events in the Eternal Tails stories so I'd recommend reading those instead unless you're interested in behind the scenes details, character interpretation, PTSD, or writing your own fanworks with a darker Tails perspective. Or you're super desperate for poorly written Old Yeller/Sonic the Hedgehog content, I guess?
I've appended specific examples in italics on top of my original notes to try and give examples or comments for clarity. Apologies in advance if any are unclear or redundant. If you'd like more detail on something please let me know via a review or a PM and I'll try to add it in.
~ Pan.
Story: Yeller dawn, the Beginning:
Miles stared out at the ocean around Cocoa island, the sheer scope of what he'd done rising up from his stomach as the rising sun painted his handiwork in grim red.
Had it all been worth it? All the pain and bloodshed? The kukku would have used the emeralds to take over the world, no mistake, but now, with their island home lost, with the last of the kukkus gone, all Miles could think about was how... easyit had been.
A splash of colour broke the shore once more. Another victim. Miles almost turned away before he noticed the splashing. A survivor?
He raced down, not sure if it was to save or destroy, until a small golden pup dragged itself shivering from the water, weakly limping across the sand.
A miracle.
Miles extended his hands to the dog, plucking it from the sand and wrapping the trembling animal in his tails to warm it. A small collar adorned its neck with a small metal tag.
"Old Yeller, huh?" Miles scratched behind the dog's ear, eliciting a small yap in response. "Well I guess I'd better take care of you."
Miles sighed, gazing across a beach littered with lost feathers and their lost owners.
"Sorry there's nobody better."
The Madness of Miles Prower
The Madness of Miles Prower tries to explain Miles' canonical behaviour in games through an explanation relating to his role as a child soldier with severe PTSD. This damaged mental state is the core of Eternal Tails, and can be traced back primarily to Tails' Adventure.
Tails Adventure: Before Miles met Sonic, before the Chaos Emeralds showed up on South Island, he was an orphan, living alone, on an island inhabited only by Flickies (sentient bird critters).
The Kukku armada, a race of anthropomorphic bird people, started wrecking Miles' home island looking for the Chaos Emeralds, and Miles mounts a one-fox guerilla war against the Kukku using a variety of lethal weapons, napalm, his own hands, a hammer, and a flying sub armed with a gatling cannon and explosives.
Unlike most villains in Sonic, these were not robots or aliens, but avian mobians.
Tails' Adventure concludes with Miles massacring all the kukku (including children, including with napalm), sinking a Kukku battleship (all hands lost), crushing the skull of the Kukku's top scientist with a rock, smashes the Kukku Emperor's mecha in personal combat (possibly bare handed) before finally sinking the Kukku's floating island fortress into the ocean, claiming all six chaos emeralds, and saving the world at the expense of the entire kukku population.
A traumatised Miles, fresh from war, barely civilised, and with no understanding of how to behave in civilised society attaches himself to Sonic, whose non-lethal approach to heroing exasperates Miles' own self doubts, leaving him passive and deferential to Sonic, abandoning his old, violent combat style to emulate his new hero in both attitude and strategies.
It wasn't a perfect fit, his experiences left him reckless, fearless, and disturbingly tenacious, even in the face of terrible injuries, but Miles' persona at this point is outwardly cheerful and playful, emulating Sonic as best he can while inwardly being terrified that Sonic would abandon him and making sure he remained as useful as possible.
Tails Sky Patrol: In the ET timeline, this happened during the events of Sonic CD, while Sonic was away on Little Planet. It is never mentioned what Miles did to Witchcart or her gang, but suffice to say they were never heard from again, and Miles has trouble being around rabbits.
Sonic Adventure: After immersing himself in Sonic's shadow for four years, Miles is forced to take on a solo role to save Station Square. He is scared, not because he is worried of failure, but because he is worried that without Sonic there he will have another Sky Patrol episode.
His success restores Miles' confidence, and from his very next adventure Miles starts using guns and explosives again, marking him as the only heroic character willing to use firearms and explosives.
The next few months are a golden age for Miles' mental health. He is still dependent on Sonic as an emotional anchor, but willing to use his full range of skills. He stands up against some of the top dogs in the setting. but sometime around Sonic Generations, Sonic stops inviting him to take a direct role in his adventures.
The effect on his psyche is devastating. Miles concludes that Sonic does not need him anymore, and makes an effort to develop a new persona that he believes Sonic wants him to be. His new persona is even more passive than before, somewhat timid, disengaged, makes use of none of his abilities, and is almost entirely devoted to creating gadgets in an effort to make sure Sonic does not abandon him entirely.
Then comes Sonic: Lost World, a dangerous time for Miles' mental health because Sonic specifically questions Miles' science ability, his one and only remaining anchor for "being useful". For the first time in forever, Miles and Sonic have a falling out. Miles stops deferring to him as much, there are arguments, and we can see some of the tension - Sonic snaps at Miles because he's worried that he will get hurt, Miles snaps at Sonic because he is ultimately terrified that this is the end, that Sonic is done with him, that he will be abandoned.
In the end, Miles falls back on his old habits - he shoots at living targets with a gun for the first time since he was four years old, in front of Sonic. Complete mask failure. But he saves the world, proving once and for all that he is the technologist Sonic needs. He is safe again, and his mask is restored and reinforced.
Then comes Sonic Forces. A double whammy. Miles loses Sonic, and his passivity - reinforced by his mask slipping in his last adventure - means that he didn't help save him. Despite his best efforts he is now on his own once more. Secondly, he is confronted with something that he hasn't faced since Tails' Adventure - war. Full scale, violent war, with casualties, a far cry from the usual adventures where the combatants are zany robots and grand schemes involving eldritch horrors or something.
Miles' mental health tanks, he experiences full scale PTSD. Miles withdraws from his friends because he has lost his emotional anchor and is terrified of himself, of killing them and everyone around him. He doesn't know what to do with himself, so his only response when faced with a threat is to simply call for Sonic to come and save him, only moving to defend himself when Sonic doesn't show up - at least until Sonic finally shows up.
Which brings us, as of the time of this writing, to "current" Miles.
Game Lore Assumptions
Golden Rule: No assumption in ET should contradict official game events. They should interpret game constructs in a sensible way and attempt to give a "best fit" explanation to the events that are already canon - like how Amy Rose showed up on Little Planet in Sonic CD, swimming being a rare skill, or how humans are the dominant species on a planet full of fuzzy little superheroes.
Sonic game canon being what it is, a lot of this stuff is actually just trying to give a reason to events that are already canon and completely bananas. As far as ET is concerned, if it happens in a game it's either
All non-crossover games are assumed to have happened: But also use a little artistic license in their execution and when they actually occurred. This usually means the games are much less brutal than the real thing, as well as significantly slowed down for human consumption. Miles is always player two in these games where possible.
Mario and Sonic unfortunately do not exist in the same universe ready to go to the olympics together in ET, they don't go to sports events against the other Sega characters, and so forth.
While Chaos Break happens in a near future of the setting after all games are finished and Eggman "wins", a ET story can fit between most games in the timeline after he is relegated to a backline role, with Miles' thoughts about events giving an indicator of where in the timeline he is, and the status quo safely restored in time for the next canon adventure.
ONLY games are assumed to have happened: The other continuities, including Boom and Sonic X, are not "native" to the game canon where ET takes place. Miles was not raised by Sally Acorn or Bunnie Rabbot, there are no other mobian foxes, and has never encountered anything Metarex related. Whisper and Tangle are a grey area, since they now exist in games, but safe to say Miles probably hasn't met them and has never experienced anything out of the IDW plotlines.
There's a bit of a grey area here - Madonna and Tiara Boobowski as off screen love interests, Sonic's real name being Nicky, Dave the Intern working at the local funfair, or Mina Mongoose performing with the Knots have all been slipped into ET at this point, but never interacted particularly meaningfully with the main cast. If you're keen on writing an IDW version of Miles, this can probably still work just fine, with a Miles who has been released back onto more active field duty and is a bit less stressed compared to his game only version.
Don't let this stop you from throwing people together and seeing what happens either. Whether you're throwing Miles into their universe or taking that character and putting them into Miles' path, just keep in mind that Miles won't necessarily "play nice" the way the local Tails would.
All non-"bad end" variations of game events are assumed to have happened or be possible: Sonic, Miles and Knuckles all use all the Super Emeralds at some time during the Sonic 3 and Knuckles event, all team variations between Miles, Cream, Knuckles, Amy and Sonic occurred at some point in the events that SAdv3 is based on.
Since Miles is never "player one", Sonic remains the series hero, even if the games prove that Miles or other characters were capable of doing so.
This means all game abilities, including those displayed by only certain team combinations are assumed to be broadly available to the characters involved. Miles can "glide" with his tails without Knuckles "in his team" because he learned while working with Knuckles. Cream is perfectly good at using a hammer, because Amy taught her, Ray and Mighty can use a super state.
Miles could potentially use his mid-air spin dash from Tails' Adventure, except I have no idea how he pulls it off. It's probably a proto-version of Sonic's mid-air light speed dash using very basic chaos control.
Mobians: The fuzzy little people are collectively called mobians. These represent multiple species all within the same genus. Like humans, most instinctively self-congregate towards their own species, but they intermingle comparatively freely, and their overall population is low enough that there's no great resource pressure pressing them into competition with one another. The low population may be related to their lax parenting strategies.
Game representation is treated as an indicator of how populous a given species is on Earth. "Avatar" species are the most populous, other species are less populous, while Miles is the only fox around. They are generally quite rare outside of the Mobian territories.
Mobians are extremely hard to injure with blunt force trauma or falling, but are critically weak to stress. Anything that does hurt them has a very good chance of killing your average mobian, even if it's in a normally non-fatal area.
In ET they are not a native species, and they are not related to Earth animals (the same as Critters, which are broadly related to Mobians and themselves at least semi-sentient). The other name for Little Planet is "Mobius", and the mobian natives there are far more numerous. Mobians "invaded" Earth from Little Planet thousands of years ago, and the territories they hold are both independent of, and isolated from, the human territories, though trade and cultural exchange exists.
It is because of human influence that female mobians wear clothes (for fashion, not utility), but gloves and shoes are common because mobians canonically have no "pads" on either. Gloves and shoes prevent static discharges, provide extra grip, and avoid mobians getting their fur caught in things.
Mobians are not a genetically stable species, and many mutants exist. The reason for male heroes overrepresenting females in the setting is because these extreme mutations are more likely to manifest, and do so more strongly, with a short "Y" chromosome. "Baseline" mobians aren't much stronger or faster than a regular human, effectively less so in many ways due to their smaller stature and lower mass. Sufficient effort can push a baseline into abnormal status, but it's a rare enough occurrence that they might have started as low tier abnormals themselves.
Even strong mobians are vulnerable to the laws of physics. Their ability to impart force is restricted by their size and weight, and even Knuckles could be theoretically restrained by locking him in a position where he cannot apply sufficient force to his restraints.
Very few mobians can swim, and those that do so achieve this either by a mutation, massive amount of body fat, or straight up super strength. Your average mobian is like a hippo - far, far too dense to float in even salt water, and they can only hold their breath for around thirty seconds. More Mobians can fly than swim, so it's a pretty big deal when one does.
This includes kukkus, making the sinking of Kukku Island that much more fatal to the kukku population.
Because they have no relation to Earth animals, mobians generally share similar traits to one another: Omnivory, warm bloodedness, blood, and a decent but not incredible array of senses and abilities partially influenced by the "type" they are. They are not strongly scent based, do not have scent glands for communication, and have a decent resistance to "everyday" toxins, like onions, chillis or chocolate.
In short, they are not a bunch of insects, reptiles and mammals that started walking on two feet, but their own genus, mobia, with broad similarities to animals due to convergent evolution, though genetics as in humans has a strong impact on behaviour and personality. Hybrids are possible, as Fang the sniper attests, but infrequent, and his lack of either "standard" clan affiliation (the Wolf/the Jerboa) indicates that they may not be widely accepted (and given that Fang is missing a finger, he may have genetic issues due to the mix).
"Anthro" is considered something of a slur among mobians, as it means "humanlike". Defining an entire separate species by how they look like you is pretty rude. They are not even hominids, as they are not ape-descendant.
Hammerspace: The ET explanation is that mobians instinctively manipulate ambient chaos energy to create pockets of space to store things in. This is how they store things without pants, where rings disappear to, and where Miles pulls out spring loaded boxing gloves, a hand cannon, and effectively infinite explosives.
It's named after Amy, who is a gifted Hammerspace user, and is dependent on the Chaos Emeralds being somewhere nearby. Without the emeralds, or if the mobian dies, the space "unfolds" and they drop all their stuff.
Rings: Rings are ambient energy condensed into a material form. If a mobian is in contact with a ring they instinctively use the energy when subjected to a harmful external force, preventing and/or reversing the injury with an ablative forcefield and rapid regeneration.
Even one ring is sufficient for this, but it is not an efficient process. "Ablating" destabilises all the mobians' held rings, which promptly explode out of hammerspace, burning out and fading away unless quickly collected and stabilised again by hammerspace.
One critical weakness of rings is that they cannot prevent "crushing" damage. The ring reaction would try to restore the damage, but fail because the outside force is still present. They also don't interact with asphyxiation. Probably doesn't interact with poison or disease either, except as below:
Contact with enough rings (approximately 100) provides enough energy to completely repair any injuries to the Mobian - a 1-up, if you will. Unlike the games, these 1-ups do not provide life after death, but can restore the all-but dead. They cannot restore lost fur, clothes, or bodyparts.
Monitors & Power Ups: Monitors interact directly with the user's hammerspace, granting the item within to them. They can be manufactured and held themselves, and can generally be found in the wilderness because a lot of mobians don't trust technology in or around their homes, even particularly useful technology. Rings, shields, anti-friction forcefields are at least a few of the types.
Shields: Shields started as simple barriers that simulated an artificial "ring response" in the user. Unlike rings, this artificial shield applies to any "dangerous" impact, even if that impact would otherwise be non-harmful to the wearer, like rings, it's a one shot ablative defence.
As the wars with Eggman went on, new types of shield were invented for both offensive and defensive purposes to allow regular mobians to better survive the hostilities. Most, except the water-specialised bubble shield, have a critical failure when it comes to submersal in liquids.
Wispons: Thanks to recent breakthroughs, wisp tech has grown in popularity, with Wispons and wisp powered technology becoming a mainstay of baseline mobians. Wisps, being cuddly eldritch abominations, are generally pretty okay with sitting for long periods of time in wisp chambers.
Magic Rocks: Generally speaking, Chaos Emeralds are mutually repulsive. They will not remain together for very long when collected, with reality and events always conspiring to separate them. The only exception is when stabilised with the Master Emerald or paired with Sol Emeralds, towards which they are attractive.
Aging: Mobian children mature significantly more quickly than humans, with gambling and driving being permitted among eight year olds and mobians featuring far more maturity, physical finesse, and ability to handle stress than an equivalent human, even if they might come across as less worldly or educated owing to less available time. As a general rule it's not really worth being explicit, but I generally double their given age as a rule of thumb to figure out they're getting up to.
As for the main cast, ages are all over the place in game canon, with Sonic going from 16 in classic to 15 four years later, Amy going from 8 to 12, and Knuckles going from 15 to 16. And that's to say nothing of Charmy Bee becoming ten years younger. ET has tried to explain this as Sonic originally being 11, Knuckles being 12, and nobody having any idea about what their actual age is or not caring very much.
Miles' age remained at eight years old because of mutual agreement. The cast as a whole agreed that Miles got his age wrong and, rather than revert his age, gave him "unbirthdays" to celebrate until his age caught up.
Sonic speed significantly above Mach 5 by Sonic can be assumed to be over short ranges, Chaos Control related, or unreliable narration. His "normal" speed is usually lower, as is shown more or less consistently in the games. Because of the way physics works, this still makes him one of the biggest bruisers in the entire setting even before turning "super".
Cursing in ET can come in several forms. "Chaos" is a mild, generic curse, "Penders" isn't fit for polite circles. Characters also might invoke the name of their patron deity - Sonic's is the holy trinity "Yasuhara", "Ohshima", and "Naka", Knuckles is "Yuda". Miles' is "Yamaguchi", and Amy's is "Hoshino", though she also might bust out an "Ohshima" on occasion.
Could probably build a whole pantheon of game developer name cameos. Yamaguchi the trickster god? Ohshima, god of Hedgehogs?
Surnames indicate that a mobian is affiliated with Little Planet (Amy Rose, Miles Prower), while title (the Hedgehog) that they are an Earth inhabitant, which holds to clan designation.
What Makes An Eternal Tails Story?
A general Eternal Tails story aims to:
1: Explore and investigate Miles' relationship with others and the world around him through the lens of his troubled mental health.
A story with Miles interacting with his friends should work out with Miles behaving exactly the same as the canonical Tails - passive, helpful, slightly snarky, and generally deferring to whichever hero he is supporting at the time. The less the person he's interacting with can interfere with his status quo, the more Miles moves towards more his more active, rational personality.
Even at peak "Tails", Miles inner world is generally very different from his outer behaviour, and even Miles himself is not particularly well aware of his own feelings. This is a combination of his masking behaviour and self doubt.
2: Present Miles with an "impossible" scenario.
This does not need to be an end of the world scenario, but does need to threaten the status quo. if a problem is not sufficiently impossible, it is probably not sufficiently difficult to present Miles with a challenge without an additional layer of difficulty. Miles might be able to handle the Return of the Kukku comparatively simply, but if he needs to do so while still maintaining his mask persona and keeping the initial kukku war secret from his friends that becomes a much harder problem to deal with.
The four foundations of Miles' problem solving ability are his intelligence, his determination, his hyper-rationality, and his heroic nature. His heroic nature leads him to tackle the impossible problem in the first place, his intelligence allows him to think up solutions nobody else could, hyper-rationality allows him to employ amoral solutions that other heroes would never accept, while his determination allows him to follow through with the plan no matter the cost.
These combine into Escalation: Miles' ability to bootstrap himself up to match the difficulty of the task at hand.
The key limits to Miles' problem solving ability is his passivity, hyperfocus and his doubt. Passivity means Miles will not proactively approach problems, especially if a hero might do it for him, Hyperfocus means Miles will frequently miss small, crucial details in his solutions, and Doubt will prevent him from using his full abilities, particularly if they compromise his mask.
These limit Miles' Escalation: He will not pre-emptively accumulate power, his solutions may not always work or have some key flaw, and he will never accumulate more power than absolutely necessary to deal with the problem at hand. He will also almost invariably get rid of any accumulated power after the problem is dealt with, returning to his base state of perhaps a few gadgets and his own natural abilities.
3: Present a Choice.
Miles always has a choice in any major Eternal Tails story where he may choose an easier road with a worse outcome, or better outcome that sacrifices the status quo or stay on the difficult path to return things to normal. He could give up and return to a comforting lie in Happy Days and Bad Seed, surrender to determinism in Chronos Divide and make a new life with Amy and Reason, accept defeat in Chaos Calamity and become a Contracted himself, or continue to repress and deny his feelings in Touching the Sky rather than accepting and acting on them.
While Miles in ET so far has almost always persevered there's nothing stopping you from writing a darker story where he chooses differently and is forced to come to terms with that choice. Sometimes the rational choice given the data you have is surrender or retreat, and Miles has no Deus ex Machina preventing him from failing or falling short sometimes.
4: Maintain the status quo.
One of the core conceits of Eternal Tails is that this Miles is the real canon Miles, just off-screen, with a glimpse into the damaged psyche of someone that's been fighting deadly combats since he was four years old. At the end of a crisis, Miles slots seamlessly back into the games, with no obvious changes on the outside, receives no credit for his achievement, and any permanent changes subtle enough to avoid detection.
Part of this is that Miles himself values stability over happiness. He is intelligent enough to improve his situation and the problems of the status quo, but doesn't. An uncertain future, even a probably better one, makes him uncomfortable.
As such Miles should constantly try to return a bad situation to the status quo, even if it takes multiple stories to accomplish, or causes a Chaos Break scenario - solving the problem, but returning himself to the beginning of the Eternal Tails "loop", but does not actively attempt to change the status quo of the Sonic series to improve his situation. Any improvements or advantages he accrues are either internal, minor, or the type to never appear "onscreen" in a game.
If you're aiming to break with the status quo and have it stick with your story, that's doable, owing to the infinite nature of Miles' looped existence, this will just produce a divergent timeline, and is more likely to be the result of other peoples' actions than Miles' own without the most extenuating of circumstance or extensive of character growth.
From a storytelling perspective, the more divergent your timeline becomes the more work you'll need to do every single story to ensure that readers know what's going on and actually care about all these extra people showing up.
If the status quo does change in an "acceptable" way and that change manage to stick, Miles will strive to protect the new status quo. Stability is control. Control is safety.
5: Stay close to canon.
The behaviour and actions for all characters should be as close to their canon personalities within the stresses of the impossible scenario and any divergence built up during the story.
While the characters of Eternal Tails have a bit more going on under the hood than the necessarily simplified behaviours shown in the games, Amy should generally swoon for Sonic, Sonic should bolt from Amy on sight, Wave should pick on Miles, and Miles should be outwardly pleasant to Wave while internally screaming at dealing with an avian.
6: Introduce all content and characters in a way that someone unfamiliar with the setting and previous Eternal Tails stories can navigate the story comfortably.
This one's more of a personal goal. Any story in the series should be one that a reader with any level of familiarity with Sonic lore can read and enjoy without foreknowledge, and be an inherently fun, compelling story in its own right. As such, like a new book in a book series, each story gets enough details added in to make sense as a standalone book, even if knowing the lore of ET or Sonic might let them catch more references or pick up on the plot more easily.
It is not mandatory to achieve all of these goals for every story, but do bear them in mind while writing if you want to evoke the same feel.
Generally speaking an ET story fall into two major categories:
"Behind the Scenes", where Miles in the absence of the series' main heroes has to stop holding back and start doing awesome things to solve impossible problems.
"Behind the Mask" where we explore Miles' relationships with the rest of the cast and his day to day life.
Story: Metalfall
A sample "impossible" plot set up. IDW comic spoiler warning if you care about that sort of thing:
A hyper-contagious virus has infected the mobian territories. This "Metal Virus" contaminates through touch with any living thing. After many setbacks and tribulations, Sonic, who is infected with the virus and losing his ability to fight it, and Silver are about to purge the virus using their Chaos Emerald fueled chaos states and the Warp Topaz, a jewel that can manipulate and teleport matter. The swarms of infected have surrounded the main cast, and even Old Yeller, Miles' beloved dog, has been transformed into a slavering mechanical zombot.
The only remaining survivors are Miles, Whisper the Wolf and Espio the Chameleon, while Super Silver and Super Sonic are overhead. Miles' tails just got bitten by Old Yeller. He's starting to turn, cowering as he waits for their plan to come to fruition while zombot Shadow, Knuckles and Old Yeller approach.
And then Super Sonic succumbs to the infection.
He attacks Super Silver. The Warp Topaz falls to the ground nearby, an unstable portal forming from it.
Miles has to deal with his infection, escape the immediate disaster, find a way to cure the metal virus with an unstoppable Super Zombie flying around… and soon to be two.