Johan El Johnson (Cardin Winchester) was "born" to the Lion not a year after his reunion with the emperor of mankind and his subsequent reunion with his legion. Johan was born via an artificial womb in the laboratory aboard the Bucephalus, the emperor's own battleship using Johnson's DNA stock combined with Omar Astarte's DNA.

This was done at the request of the Lion as he himself had no love of his own or who he could have children, but as Johan was growing up the Lion had decided not to tell his son of his origins.
Johan had a... Harsh upbringing under his farther, from trials that would make those of other legions jealous with envy. from having to hunt many of the beasts that dwelled on Caliban often without aid or escort being only armed with a Calabanite sword and hand crossbow.

During one of Many of these trials Johan now aged 7 by Terran years and by normal human standard years was tracking through on of the many forests of Caliban looking for a large serpentine beast only known as "the Grimm fang" supposedly being quite famous for having one large singular fang jutting out of its mouth.

whilst tracking it down Johan had come across an old ruined temple and using his intelligence to search his memory for any mention of this place but his superhuman mind unable to dig up any possible references to anything like this in his memory concluding that this was a previously undiscovered landmark.

His curiosity getting the better of him he enters the temple having to navigate through many ruined rooms and rubble filled, when he ever finally got to the main chamber having to move a collapsed white marble pillar out of the way.

What greets his eyes is an altar with an ancient mace on it but there is something odd about this weapon, it had no visible power nodes but instead appeared to have some sort of power system built into it, Johan remembers himself as saying "such fine craftsmanship gone to waste"

When he 1st picked it up, he noticed it started to glow, not with psychic magic but with a natural power, a bright red power field had formed around the head of the mace, discarding his sword in favour of the relic mace commenting "this will be my weapon that will see me to greatness"

With a new found confidence with his new find Johan set out track down the Grimm fang beast...
Days later he had returned victorious baring the fang of the beast as well as his new found weapon to applause and praise, and had finally completed the last of his farther trials and was allowed at long last to join the legion properly and receive his power armour.

His power armour was a stylised artifice grade MK3 iron armour with his helmet being mk2, unlike a vast majority in his legion Johan had chosen a dark green for his armour with black accents with his breast plate having an engraved lion holding a sword and shield in its paws, on the left with the serpentine beast on the other side holding Johan's new energy mace.

As it turns out the mace, he found was an old legendary weapon from Caliban's distant past and was thought forever lost in a devastating war, this in turn had the locals and some of his legion calling him "Artemeno" supposedly the name of the warrior who used it last when it was seen on a battlefield.

Over the next couple of years, the Lion and 1st captain Luther and the captain of his body guard Antinious had stepped up Johan's training with the Lion taking a keen interest in honing his son's skill with the sword as well as command skills which Johan took to very well in terms of small-scale operations and infantry spear head assaults which had moulded him into an excellent commander in both the raven wing and his own order of knights the "arrow wing" so named for the nature of Johan's leadership style.

Johan in his upbringing had absolutely despised Luther from the start, something about the way Luther gave him dirty looks and his vicious training methods especially after his farther would praise him. However, Antinious, his bodyguard captain and chosen praetorian was much more pleasant to get along with even with Johan's long running difficulty with social situations beyond short conversations and or battlefield orders.

However, over time Johan had grown very attached to Antinous the two often sharing quite long periods in one another's company which had started to chase Johan to start feeling... "Funny" around his guardian, something of which has greatly annoyed him as he couldn't quite figure out what exactly the feeling was.

One day whilst training with his farther with his mace, Johan takes of his helmet and with sweat pouring down his face looks up at his dad and works up the courage to ask "farther, I have a question... It's something that has been clawing at the back of my mind since I've started feeling it"
The lion turns to face his boy handing him his power mace back by the head saying "what is it my son?" he ends his sentence by kneeling down to better meet his son face to face.

Johan takes a few moments before answering with " I've grown quite fine of Antoniuos's company... It's stirred something inside myself I can't explain" Lionel's eyes visibly widen a fair bit of realisation as he says "is it like a longing towards your male companion? If so then that is a love between two warriors who have fought alongside each other more than once, it's a perfectly natural feeling my son" Johan seems to acknowledge that's what it could be but catches two serfs, a man and a young woman locked hand in hand singing each other's praises in bed in a local dialect.

Johan seems to have an epiphany as he says "no, it's a romantic attachment farther... or at the very least an incredibly strong warrior's bond " he says flinching expecting to be sent flying across the room for an apparent failure as Johan has had that happen for just speaking out of turn to his farther before...

What he wasn't expecting is for his dad to pull him into a big and awkward hug due to their respective power armours sizes and designs. After a few moments Lionel speaks "it's a perfectly natural feeling my son, I'm glad you've found someone, as per Lex dictae primarchae law I need to approve of this and you have it my boy, go to him."

And with that over the course of the next year the half primarch and the astartes captain had embraced in a rare type of relationship even amongst the transhuman of the legiones astartes and primarchs and over time Johan's own arrow wing had produced a stellar combat record especially being deployed to death worlds being famed for their lightning-fast assault tactics.

But it all went downhill from there... The hours heresy had begun...

The Lion out of fear for his son's safety had sent him and his entire arrow wing company back to Caliban to defend it against roaming hands of Night Lords or Alpha Legion. Johan had spent most of his time during the agonising wait trying to fortify Caliban and keep up the reserve of recruits to them send of fight with his farther.

However, something was deeply wrong... Luther and many of the men under his command were... Distant, uncooperative, outright vicious in response to his commands, nothing was adding up in Johan's mind as to what was going on, he had hoped it was nothing and retired to sleep for the night but was suddenly awakened by the crack of bolters and the smell of burning Ozone.

Johan is already in his armour getting into his power armour when Antinious comes running in, his black power armour drenched in astartes blood, his power sword casting a green glow across the room, it's clear Antinious was caught mid arming up as his arms are only covered by a torn body glove as the rest of him is the fully armoured in artificer grade MK4 maximus.

Johan shouts through his vox grill "what is happening! Night Lords?" Antinious with a heavy heart and a tone of mourning responds " Luther...we've been betrayed by our own brother's...my Prince, we must get you to the sanctum! Only there may we hold until your farther returns with the legion! "
Johan feels tears well up in his eyes at this but grips his ancient mace igniting its power "then if we're to die, I'd gladly do it beside you my chosen man"

the two make their way through the burning halls of the palace and fortress cutting and butchering their way through their traitor brothers and the human serfs that joined them, Johan's relic power mace making mincemeat of power armour as they run. Fire pours out of nearly every window, husks of what were once astartes... brothers had turned on brothers... and each one was breaking Johan's heart further beyond repair and making him deeply resentful...

Eventually reaching the Lion's sanctum Johan is greeted by only 12 of the Ravenwing, Deathwing companions and his own arrow wing and his own companions, all of them severely wounded and battered with the Deathwing terminator apothecary was working over time to heal wounds and patch armour where he could.

The terminator praetor with his power axe and assault cannon strides over to the two new arrivals "my Prince and captain it is good to see you in good health. Tell me have any other of our brother's come to our defence?" He asks with a large melta gun base blast in his right puldron. Johan responds "No... I fear we are all that's left of those loyal to the Lion here, I will be forthright and say that we will likely all did here in this chamber"

The raven wing assault marines revs his chain sword as he chuckles "then I will be honoured to fall in your defence my prince! Honour to the lion and Caliban!" The sentiment is repeated by many of the other astartes present as Johan smiles inside of his helmet as he turns his head to his lover Antinious and he says " together then my champion? " Antinious chuckles twirling his power sword "to the gates of hell itself, if need be, my Prince"

It only takes a few minutes for the traitors to start thundering down the halls and reaching the sanctums large marble doors, Antinious having picked up a storm shield stands at the front of the group with Johan at the back with his relic mace ready to smash and send all those who face him and starts a speech "sons of Caliban and Terra! To have served with you has been an honour! The boatsmen awaits us all with open arms! I say we make him wait a little longer!"

As he finishes the marble door is blown clean open and send shares of stone outwards battering against the power armour of the beleaguered defenders, the cataphractii terminator starts opening fire with his assault cannon shredding traitors as they rush through the breach hot spent shell's being spat out the side of the weapon.

A brutal melee ensues with Johan getting a few lucky shots in with his relic mace before drawing his shield and leaping into the melee alongside the rest of his brother's. He plants his feet well surging power into his arms as he swings out in front of him in an arc catching a traitor by the throat decapitating him under the sheer force of the blow before following through into the next one with a thrust of his mace.

When theirs finally a short break in the fighting the only surviving member of the group that had survived was the severely wounded and battered cataphractii terminator Deathwing never who looks at Antinious and tosses him a key" there is a secret fault through a passage through that door! Take the prince, make your stand there! "

Antinious takes the key and unlocks the door and ushers Johan through it but before they start running Johan asks "what's your name?"
the terminator turns to him and says "Athurion my prince, go!" The pair make an escape and slam the vault door behind them as the dim of battle resumes.

Once in the fault in question they see bank after bank of heavy bookshelves with the most interesting part was an ancient teleportation pad, the two lovers don't have long before another explosion is heard and Antinious looks at Johan "they've breached the door, they'll be near in moment's, my prince... no, my love please take the teleportarium and go... save yourself, the lion has lost to many sons, you don't need to die here"
This has Johan freaking out as he and his love take of their helmets "no... if I'm to die I'd gladly do so by your side, I'm not abandoning you my champion"

Antinious weeps a bit "I'm not asking you to do that... I'm asking you to survive please Johan... I don't want to have your blood on my hands to"
The prince responds " then at least give me one thing " Johan despite not being particularly strong pulls Antinious by his neck guard and pulls him into a kiss, the kiss he wishes could have been done under better circumstances and doesn't last long before he pulls of "should I return, I shall make your tomb personally" he takes a few steps onto the teleportarium and starts charging it up.

Johan puts on his helmet "die well my champion, Caliban needed better sons like you" the pad starts to charge up with energy but before he disappears, he sees traitors running into the chamber but before combat is joined Amtinious shares his last words "I couldn't have asked for a better Prince and lover, goodbye" he finishes turning to face the traitors and lets out a mighty roar of defiance and frantically charges into the fray once more content with his death.

Johan can see the angry eyes of Luther right before the light engulfs him and he is teleported out of there and a bolt shell detonation sends a finger sized fragment of Antinous's ceramite which lodges itself into Johan's breast plate as the light engulfs him...

Johan doesn't know how long he's been out for when he ever finally comes too, he's in a forest next to a town? Had he teleported to another part of Caliban? His thoughts are distracted when he hears what is definitely not a Caliban dialect of galactic common but something else entirely...

His thoughts turn to grief at the loss of Antinious and Luther's betrayal... With a loud rumbling roar, he takes his helmet of and slams it into the nearest tree leaving a permanent MK 2 helmet shaped dent in its bark.

He topples over slumped back against a tree crying when a small family of ginger humans come rushing up to him after a few moments with the man looking absolutely shocked as he asks "what's your name?... are you hurt?"
Johan welding turns his head and noticing the Albian/Britannic accent answers "Cardin... my name is Cardin..." He says using a false name to potentially hide himself should the situation devolve.

to be continued...

Notes:

Cardins primarch name is a language Easter egg, bonus points to whoever figures it out!