In this au or scenario is when Wind Archer gets corrupted into Night Raven and just went hide in the darkness, meanwhile Fire spirit connected to him by a string, sense his pain and corruption so he rushes over to save the love of his life
P.s I have very little knowledge of the story of Cookie run oven break so feel free to explain a few things to me

In the dragons valley it was just another normal day for Fire Spirit cookie ruling over as the fearsome Lord of flames, earlier he got a message that was summoning all legendary elemental cookies for a meeting, he thought it would be a perfect excuse for him to go meet Wind Archer cookie but sadly his business at the dragons valley was holding Jim back so he has to attend the meeting a little late, it was only once he was done with his business that Fire spirit cookie felt his flames weakening and fading away... Slowly turning him into the Lord of Ashes, Fire spirit cookie panics as he doesn't understand why he was getting weaker and turning into the lord of ashes as he feels a heavy pain that beats within his chest, he looks at his hand to see the red string and finally recalls something...
Back when he and Wind Archer got their first mission together as a pair they faced a cursed ancient relic that ties the bond between 2 cookies and revealing who their soulmates are, the relic would then connect the soulmates with a string to represent their bond together, so when one of them is in great pain or danger the other will be able to sense it as well, the 2 of them did accidentally activated the relic and thought that nothing would happen science there couldn't be any chance that they would have a soulmate but oh how fate has it surprises... The relic ties the string to both Fire spirit and Wind Archer making them soulmates, from that point on they both had a hard time processing that mission but soon grow to have feelings and eventually got together.
Now finally understanding why he is growing weaker, Fire Spirit quickly dashes out of the dragons valley as fast as he can, hoping that he's not too late to save Wind Archer but he also couldn't stop thinking... What happened? What could have harmed  the guardian of the millennial forest? The elemental wind guardian? Aren't the other legendaries there with him as well?! Fire spirit became more and more desperate to see Wind Archer to find out what happened for himself, he could only pray nothing bad really happend and it was all in his head...
Fore spirit cookie finally arrives at the millennial forest and was shock to see the trees burnt, some fallen down, others seem to be frozen, is that the work of Frost queen? How could this had happens? If someone were to harm the trees Wind Archer would never let them escape with their lives! Fire spirit flies around and calling out for Wind Archer but no response until he finally encounters Moonlight, Sea fearie, Frost Queen and Millennial tree cookie, most of them were badly injured

Fire spirit: everyone...! What the heck happened here?! Why is everything burnt and destroyed?! And where's...
Moonlight: *cough* Dark enchantress send a army to the forest... And separated us all from each other... We all split up to fight all the cake monsters but they kept on coming...
Sea fearie: Wind Archer was doing his best to subdue the endless cake monsters but one of Dark Enchantress minions Pomegranate cookie approach him with some kind of... Crimson poison, she used the poison on him and it... Corrupted him...
Fire spirit: it... What?!
Frost Queen: *sigh* we try our best to help purge him of the corruption but it didnt work... It injured him terribly and he transformed into another cookie... Next thing we knew he fled away from the screen... Leaving behind nothing but withered black feather from his wings....
Fire Spirit: then where is he now?!
Millennial tree: I am sorry... But I do not know... He's somewhere in the forest but my roots cannot see it... The corruption has clouded my view of him... The child of the dessert dose not have munch time.. He is fighting against the darkness as we speak... But if he fails to hold on any munch longer... I'm afraid we might lose him...
Fire spirit: like hell if I ever let that happen! All of you can go recover and fix the forest, I'll find him, I'm the only one that can anyways...
Millennial tree: be careful Fire spirit... He might not want anyone to approach him...
Fire spirit: thats not up to him to decided today, try to get sugar swan cookie to see if she can help, I'll light up a signal in the sky to tell you if i found him
Moonlight: we wish you the best of luck....

Fire spirit heads off into the woods, following the traces of black feathers while they are still there, they all seem to be slowly disappearing so he has to hurry, Fire spirit flies to all of Wind Archers favorite places in the forest, from the trees where he likes to rest on, the high mountain cliff where he could see the entire view of the forest to the water fall where he occasionally visits with the cookimals
Nothing.... Wind Archer was simply not there, Fire spirit became more and more desperate as he fails to find the love of his life in his favorite areas, could Dark Enchantress have took him away? No... He wouldn't... There was only one place that Fire spirit hasn't checked yet and it was the deeper part of the millennial forest, shrouded in darkness and mystery, Wind Archer once suspect thats where the fallen spirits that occasionally cause trouble for the forest comes from but refuses to enter and dealt with them because millennial tree said its best to avoid that part of the forest, Fire spirit was unsure if he could ever find anything here but he knows he didnt had a choice because Wind Archer is waiting for him! So he march first right into the dark forest.
As expected the forest was so dark a normal cookie wouldn't be able to see anything so with what little strength he had, Fire spirit light up and a little fire to shine his way, he sees how the trees here are withering... No forest animals are even present... No birds or squirrel  in sight... It almost feels like the life was sucked out of this side of the forest... Why didnt Millennial tree cookie do anything about it? Going deeper into the forest, Fire spirit saw a strange vine on the ground... It was out of place... Definitely does not belong to any trees... It was dark black with the essence of corruption... He's closed... Fire spirit follows to where the vine could possibly lead to, it was getting bigger the closer he gets and he could feel the corruption energy growing as he keeps on going and then he finally saw it... Looking up from the vines, Fire spirit saw a giant black orb floating in mid air and the orb was connecting itself to a tree stump, making it withered and corrupt, it almost felt like the orb was beating... But Fore spirit cookie only focus on what was in the orb... It looks like something is hiding itself inside the orb with its wings... Could this be...
Fire spirit approach the orb and reaches his hand out

Fire spirit: Windy...?
???: DONT COME ANY CLOSER!!

The cookie in the orb shouted and spread his wings causing a force of wind knocking Fire Spirit cookie back away, yup thats Wind Archer alright... Nobody could com pair to him in case of making a wind force to push them away... He has done this to Fire spirit every time he's angry at him...

Fire Spirit: Windy I'm here to help... You can't stay like this...!
Night Raven: I'm not Wind Archer anymore... Its Night Raven.... And there's nothing you could do... This corruption that be subdue... It has caused me to destroy the forest.... It made me hurt the great tree... And it'll make me hurt you too...
Fire spirit: no it won't, c'mon Archie... You know you never hurt me... Your just hurt thats all, once we bring you to Millennial tree and Sugar swan I'm sure they'll know what to do... And you'll be back before you know it... Besides its not like Millennial tree could ever get mad at you
Night raven: why wouldn't he when I destroyed his paradise... I don't deserve to be save...
Fire spirit: Wind look at me! You can't say that! Dark Enchantress and her stupid cake puppy army merely caught you off gaurd! You would never let yourself get corrupted and destroy the forest and you know it! You spend your entire life dedicating to protecting this forest so why stop now? You can still be save and still help millennial tree as you always have if you fight this corruption, and you won't do it alone, I'll be right here by your side fighting along with you! So there's nothing for you to fear!
Night raven: why... Why would you want to save me... I've become nothing more then a corrupted falls spirit...
Fire spirit: and what kind of question is that? I want to save you because I love you, I'm a fallen spirit aren't I? Then you and I can be fallen spirits together! I will spend the rest of my life protecting you as you dedicated your life to protecting the forest...

Fire spirit holds Night Ravens face and brushes a little hair to the side as the blindfold on his face disappears letting Night Raven open his glowing purple amethyst eyes to look right into his ruby red ones, Night raven slowly bring his hand to touch Fire spirit cookies hair to caressing his face

Night Raven: your hair... You flames... They are extinguished... What happened...?
Fire spirit: soulmates remember? I guess when you got corrupted I kinda grow weaker... But its fine, once we cure you it'll all go back to normal
Night raven:... I'm sorry..
Fire spirit: hey there's nothing yo apologize for... From now on I'll protect you... Hell I'll protect all of earth bread if thats what it takes to love you for the rest of my life!
Night raven: hehehehe... You always have a strange way with words...
Fire spirit: just for you

Fire spirit cookie lifted Night Raven into his arms bridal style and flew them both back to the other legendary cookies, luckily Sugar swan and Millennial tree manages to turn Wind Archer back to normal but they couldn't fully remove the poison, this worries Wind Archer greatly but with Fire Spirit holding his hand tight, he sighs in relief, knowing that he will be just fine...