I should not be thinking about what I want to write after Crossed Sparks is done, because there's still so much to go, but I've been having this idea for like... I guess you could call it "AU of an AU", because it borrows a lot of elements from my Sparks worldbuilding.
I call it Ghosts AU.
Set after the end of TFOne, everybody is trying to pick up the pieces and figure out what comes next. Optimus is struggling with leadership and feeling isolated from his friends and still mourning the way his relationship fell apart with D-16. He also can't shake the feeling that more people knew about Sentinel's deception than they thought —especially so when someone breaks Airachnid out of custody and she disappears into the night with Sentinel's mangled corpse within days of the fallout— but he can't prove anything. It does make him anxious to trust in the members of the governing body, not until he can prove that they are above suspicion.
Following Elita's advice, Optimus tasks those he trusts the most to hold the fort for a while —Prowl, Elita and Jazz to handle reorganizing their society along new, better principles and Bee to investigate who stole Sentinel's corpse and why— and goes into solitary meditation to get in touch with the Matrix. Unexpectedly, this idea bears fruit: the Matrix grants him a connection to the ghost of Zeta Prime, who starts acting as a confidante and mentor to the young Prime. Optimus quickly comes to rely on the ghost, but it's fine. Zeta is uniquely qualified to advise him on his new position and his new duties, to coach him through the hurdles of leadership like nobody else can, to teach him everything he needs to be to live up to the expectations of his new station and more. So much more.
At the same time, Bee teams up with Ratchet, the medic having noticed something in Sentinel's body when he briefly scanned it after the battle. Though he doesn't know what exactly was wrong with Sentinel, he is not constructed like a normal mech. There is something nasty lurking under the surface, something they must uncover if they want to have any hope of finding out what happened. Together with Bee they dig into the history of the city, the war and the Primes, working against time because as Elita and her team try and silence the dissent and doubt rising up against an absent, untested and untrained Prime, fewer and fewer mecha are willing to speak to them and their leads dry up one after another when the bots who should hold the answers are cast out to the surface on suspicions of conspiring with Sentinel or spying for Megatron or the Quintessons. They are chasing after ghosts that slip out of their reach every time they come close to uncovering the truth.
Megatron is not having a good time either. Their base is discovered by the Quintessons, forcing them on the run, leaving him no time to mourn Orion. Worn down by the constant fighting, they try to escape yet another Quintesson attack by cutting through an old battlefield, hoping that the Quints would lose their trail among the wrecked starships when someone —something— unexpectedly comes to their rescue. The Damocles is an old ship; heavily armed and armored, its central AI infuriatingly opinionated and headstrong, but like all other ships of its make, it can't function independently. It needs a crew and they need a base. In the newfound safety of their temperamental flying fortress, Megatron can finally take the time to mourn the bridges he had burned, and in his sorrow he finds support where he least expected it: in his dreams and his lonely hours, Megatronus Prime appears before him, offering him support.
The past haunts the present and it's only a matter of time before these threads all run together...
