Queen of the Castle au Part 2
Lucifer and Lilith are dead but succeeded in killing Roo so Charlie is safe from being used as a vessel by the Root of all Evil like Eve was.
Unfortunately Roo's domain (Purgatory) is quasy sentient and without her to keep it in check and support it, it eventually starts to unravel and goes searching for a way to sustain intself.
To stop itself from unravelling it begins to plunder the 2 neighbouring divine realms, Heaven and Hell.
It starts slow, nibling away at the edges of both realms but eventually once strong enough it starts to canabalise both realms.
This is 2 centuries after the Deaths of Lucifer and Lilith so Charlie is 233 years old and has been ruling without a regent for 83 years.
She's established herself and garnered the support of the people so when reports on Purgatory reach her she manages to marshal all 7 rings to work in unison to defend Hells borders.
The Sins did not want her anywhere near the fighting but a fluke incident proves that combining Celestial and infernal magics has a cripling effect on purgatory (side effect of Lilith and Lucifer working together to kill Roo) making her their best weapon to ensure hells survival.
Adam is sent to investigate and upon realising that Purgatory is attempting to devour Heaven and Hell, he and Sera try to contact the Arch Angels so that somwthing can be done.
After Lucifers fall his siblings and father distanced themselves from the rest of Heaven and dont really respond to messages, prayers or scrolls anymore.
In a desperate act Sera sends Adam to negotiate peace with Hell and try to combime their forces against Purgatory.
Adam thinks its pointless, until he meets not Lucifer but Charlie.
Adam has yet to be completely hardened by the centuries and as much as he hated the people Lucifer and Lilith became, they were once his friends so he finds himself grieved by their passing.
Some of his anger at the 2 is also quenched by the knowledge that they killed the monster that ate his wife, finally setting right the mistake they made all those years ago.
Also, he can recognise that Charlie is basically a baby by angel standards and should not be dealing with everything she is.
Adam is a dad, those instincts don't just go away. Charlie manages to trigger all of them so its hard to feel any anger towards her despite how hard he tries to hold onto it.
The two of them are able to begin tentative but genuine talks for an alliance and after Adam lets slip that he knew her parents she asks him to tell her about them.
Talking about Eden hurts but not as much as it would have before learning L&L deaths. lt's a form of mutual grieving and also seems to help Adam heal and move on from the pain that has haunted him for so long.
They continue to meet and form plans to create squadrons of hellborn and excorcists to work together in fighting off purgatory.
They intend to starve the realm out.
If they destroy enough of it and it cant feed on Heaven and Hell, eventually it will either consume itself or unravel.
Either way it will be gone.
Adam eventually trains Charlie so that she can combine the fighting methods of Heaven and Hell. Its nostalgic given Lucifer was the one who trained Adam.
Adam becomes Uncle Adam at some point to his and the Sins dismay as none of them wish to interact but are now forced to for Charlies sake.
Vaggie is sent by Adam to act as Charlies bodyguard after an Assassination attempt. (Vaggie and Lute talk constantly as Lute mentored her and has alot more experience supporting and protecting a leader who refuses to stand on the sidelines).
He also convinces Sera to let Charlie and Emily be penpals, Charlie needs a friend who isnt a subordibate and he hopes that Emily will remind Charlie to be a kid and indulge ocasionally.
She may be Queen but she is also a child who needs to experience some childhood happiness.
In this world they have no exterminations because Charlies rehabilitation and integration programs accidentally caused redemption.
They are also never even argued for because both divine realms have bigger priorities.
Instead they have the Second Great War or War of Worlds as some call it.
Heaven and Hell are growing ever closer with trade booming between the 2.
Technological and medical advancements in Hell are booming as they tend to do in war and this bleeds over into Heaven somewhat. (Medical advancements develop especially fast in order to support their queen)
Heaven is keeping the war secret from the Winners and basically all Angels not involved in the army or council so it isnt seeing the same development boom beyond what bleeds over from hell and the military but that is still enough to put them ahead of where they were in canon.