Like:

“I feel a fjerdan man seeing ankle for the first time.”

“This sentence would kill a fjerdan child.”

“Not to sound like fjerdan woman suffering from hysteria—”

we can start with when he became drüskelle. the strongest quote for that is from crooked kingdom, chapter 15: “He’d been twelve years old, new to the drüskelle, and every day he’d thought about running away. He didn’t mind the training. The hours spent running and sparring helped to keep the longing he felt for his family at bay.”

that already tells us a lot. by twelve, matthias is already considered part of the drüskelle and already in training. he’s also drüskelle enough to be taken to the ring of stones to claim an isenulf. and in that same chapter, he says, “Sometimes there are more wolves than drüskelle, sometimes more drüskelle than wolves.”

that distinction matters.

now i need to bring in a couple of things from six of crows about initiation and hringkälla. hringkälla happens on the spring equinox, so in march. nina explains it very plainly: “Hringkälla. It’s the Day of Listening, when the new drüskelle are initiated on the White Island.” then matthias adds, “On Hringkälla the drüskelle finish our initiation,” he said. “We go from aspirant to novice drüskelle in the ceremony at the sacred ash.”

so there are stages to becoming drüskelle. first, an aspirant becomes a novice drüskelle through hringkälla, if he can cross the secret bridge and complete the initiation. then later comes the next major threshold, when he captures and kills his first grisha. that’s what earns him his teeth and allows him to grow his beard.

six of crows, chapter 14: “Good work is right,” one said in Fjerdan. “Fifteen Grisha to deliver to the Ice Court!”

“If this doesn’t earn us our teeth—”

“You know it will.”

“Good, I’m sick of shaving every morning.”

“I’m going to grow a beard down to my navel.”

and hringkälla is not some open, equal test either. matthias explains that too: “In truth, elder drüskelle simply passed the secret of the crossing along to aspirants they wished to see enter the order; it was a way of culling the weak or those who had simply not meshed successfully with the group. If you’d made friends, if you’d proven yourself, then one of the brothers would take you aside and tell you that on the night of the initiation (...) Commander Brum himself had been the one to tell Matthias how to find the secret bridge, as well as the trick for crossing it undetected.”

and that is exactly why the ring of stones scene matters so much. if you’re being taken there to claim an isenulf, you should already be a proper drüskelle (novice drüskelle). you should already have crossed the secret bridge, passed hringkälla, and been accepted into the order. they’re not handing wolves to boys who are still only aspirants and might never make it through initiation.

so if matthias is twelve in the ring of stones memory, and he is already “new to the drüskelle” that means he had already been brought into the order by then.

and this is where the date matters. hringkälla happens in march. from the crooked kingdom collector’s edition, we know matthias is a taurus, which places his birthday somewhere between april 20 and may 20. so hringkälla would happen before his birthday.

that means if he was twelve and already new to the drüskelle, already in training, already in that stage of being taken to the ring of stones, then the initiation that made him novice drüskelle had to happen before he turned twelve. and the text around it supports that he had already been there long enough to be absorbed into the group’s logic. in six of crows, matthias says, “If you’d made friends, if you’d proven yourself, then one of the brothers would take you aside and tell you that on the night of the initiation.” and in crooked kingdom he also says, “Brum had warned him that he would never become a true drüskelle if he did not learn to see the other boys as his brothers, but Matthias didn’t believe that. He was the biggest, the strongest, the fastest. He didn’t need to be popular to survive.”

to sum it up, the cleanest reading here is that matthias became a drüskelle at eleven.

i’m almost done, bear with me. what surprised me is how many people don’t realize he was seventeen in hellgate and turned eighteen there.

we’re still around february or march in six of crows, when the crew is gathered together for the first time in the crow club, because nina says, “It’s seasonal, on the spring equinox.” and then inej notes, “Two weeks from today.”

matthias is eighteen at that point. and thanks to nina and kaz repeating it over and over, we know he had already been in hellgate for about a year, maybe a little more. so that puts him at seventeen when he was sent there.

six of crows, chapter 20: “The shipwreck had been more than a year ago, but it felt as if no time had passed at all.”

papa helvar was big and burly. his hair was brownish-blond and going grey, and he had stubble that never fully grew into a beard. he would lift matthias onto his shoulders, even when he started to grow older and bigger. he taught matthias how to whittle and carve wood. he was kind to every creature, and often would be seen nursing small animals back to health. he took pride in his small vegetable garden. he hated the druskelle. he loved sheep.

mama helvar was tall and muscular. her hair was long and so blonde it was almost white. she would sing matthias lullabies and tuck him into bed with a little stuffed wolf every night. she would chase matthias around the house, and when she caught him, would shower him with tickles and kisses while he squirmed and complained through giggles. when she was pregnant, matthias would give her massages and bring her little gifts of flowers and food and stay by her side as long as he could get away with. she called him “mattie”. she loved wolves.

has a huge amount of affection towards any animals

pulls out a crouching position and 'pspspsp' whenever there are cats around, you'd never believe that he was a trained druskelle for the way he acts around cats, he's a huge softie

although he wouldn't admit it at all, during the planning phase of the ice court heist, he revelled in sleeping in, for the first time in his life, even if he was hesitant to around nina and kaz

can braid hair really really well - when he had his long hair when he was a druskelle (before hellgate ) he would braid it often

when on the outside he pretended to be scared of nina being able to speak fjerdan like a native, he thought it was really attractive, and for the first while of knowing her, got quite flustered when she would

when him and nina finally moved in together, he would make sure she was warm every night - often with a horse blanket :)

in hellgate, he would sing songs in fjerdan to go to sleep and try not to think about nina

he really likes to journal, but since he is so afraid of people finding out about his feelings, he uses codenames for everyone in it, and if someone finds it and asks him about it, he denies and denies

gets up absurdly early in the morning - even earlier than nina, because thats what he has been trained to do since he was so young

has a insane tolerance for alcohol, and it takes him at least four drinks to get tipsy at all

has a suprisingly nice voice in compare to nina - but doesn't sing very often, nina only realised when there first son was born, and matthias would sing him to sleep

is very soft for children, as he knows what its like to not feel cared for, especially considering his backstory

gets really anxious initially when he moves to ravka with nina, as for a long while, he often got horrible stares from natives, who would sometimes even spit at him

found a way to bring trassel to ravka, and trassel ended up loving nina, even if she was grisha

has lots of scars, especially one on his shoulder from when trassel bit him as a child, but won't let nina tailor them away as he sees them as reminders on his body

loves giving nina little pecks on her lips when he walks past her, and is very very affectionate

is so protective of his and nina's son (haven't figured out the lore for that quite yet) and taught him how to fight

when he gets drunk, he's really playful and droopy, often giggling a lot and leaning over nina

when he gets sick, he is insistent that he is not, and he pretends that he's not, but nina immediately knows when he is, because he stays his distance from nina

holds his breath whenever druskelle come into ravka

calls nina every pet name under the sun, but if the other crows are around she's just nina, but he's very very affectionate when its just the two of them

likes to tell their son life lessons through retrospective stories about his own life, - like persistance through nina surviving the withdrawal phase of jurda parem, and family through him leaving the druskelle for his new family - the crows

And he does not know, as we learn in chapter 35 straight from Jarl Brum’s own mouth, because they don’t, at least in the typical sense of the word, actually execute the Grisha; for the past fifteen years they’ve been torturing and experimenting on the Grisha prisoners found guilty during the trials.

Jan Van Eck: Imprisoned (possibly put in an asylum).

Pekka Rollins: Lives a rich lifestyle with his son somewhere.

Tante Heleen: Her brothel went out of business. Lives a rich lifestyle, possibly started a new business somewhere else.

Previous King of Ravka who bankrupted the country, did nothing but rape servant girls: Sent off to live a rich lifestyle while he still can (shortened life because of his sickness).

Previous Queen of Ravka who did nothing but spend money and only protected her favourite servants from the King. But later removed her protection from Genya and let the King rape her: Gets sent off to live a lavish lifestyle in sunny Southern Colonies.

Jarl Brum, a genocidal maniac, who revolutionized Grisha hunting, made new weapons, new strategies, new training systems just to hunt down Grisha in every corner of the world to kindap them, dehumanize them in countless ways, experiment on them and later kill them. The man who either killed Grisha after a sham trial or drugged them until they died, who forced Grisha women to get pregnant over and over while drugging them, the man who bombed Ravka's capital, who draws satisfaction from their suffering because he thinks Grisha are vermin and insult God by existing: Gets spared multiple times and later loses his rank. Because apparently, he's "only a product of the system and Fjerda made him that way". As if he wasn't the main force enforcing that system, as if he didn't brainwash children and made them make killing as many Grisha as possible their life goal.