[SPOILERS for those not caught up on Agents of S.H.I.E.L.D. ahead.]
Ghost Rider returns to do battle with the now-Inhuman Aida in the trailer for next week's Agents of S.H.I.E.L.D. season 4 finale. The final episode of season 4, 'World's End' will further tie together the different narrative throughlines (or "pods", as the showrunners have been calling them) explored over the course of the show's fourth season. That list includes, the introduction of Gabriel Luna as Robbie Reyes/Ghost Rider in the season's first third, followed by a shift in focus to the Life Model Decoy known as Aida (Mallory Jansen) and Aida's subsequent use of The Framework/Project Looking Glass as a means to make herself, quite literally, human.
As was revealed during the penultimate episode of S.H.I.E.L.D. season 4, 'The Return', the human Aida is in fact an Inhuman and she posses extremely dangerous abilities that include teleportation and self-healing, among other things. Robbie as the Ghost Rider only returned at the very end of 'The Return' so it falls upon 'World's End' to explain what, exactly, it was that brought the Spirit of Vengeance back to our world - though based on the trailer for the episode, we can hazard a guess.
Seeing as Aida intends to "burn this world to the ground" (as she puts it in the 'World's End' trailer, above), odds are that whatever powerful forces govern the Ghost Rider in the Marvel Cinematic Universe have decided to intervene and return Robbie to our dimension, rather than allow Aida to bring about whatever apocalypse she has in mind. Agents of S.H.I.E.L.D. has firmly established that the Spirit of Vengeance is all-but-unstoppable once it has decided to go claim someone's soul; making the answer to the question that Coulson asks Robbie in the 'World's End' trailer ("This thing in you - is it as desperate to destroy Aida as we are?") all the more essential to our heroes' survival.
Considering that Ghost Rider comic book stories are typically steeped deeply in the supernatural horror genre and the Life Model Decoy/Framwork storylines on Agents of S.H.I.E.L.D. are heavily based in high sci-fi tropes, it's a testament to the quality of the writing during S.H.I.E.L.D. season four that these elements have been woven (for the most part) seamlessly together. That also goes for the return of Ghost Rider in the season finale, as it was the mystical book known as the Darkhold that figured prominently throughout Robbie's original story thread - and as the Darkhold was the catalyst for Aida building the Framework in the first place, it's only fitting that its "keeper" be the one who should come back to stop her world-ending plans.
Perhaps the big complication to that matter is the fact that Aida is now a human whose rage and pain comes from a deep emotional wound, begging the question: will the Spirit of Vengeance decide that she is worthy of being "judged" now, or deal with her in some other manner than claiming her soul and burning her away? Either way, Aida isn't going down without a fight, so the inevitable showdown between her and Ghost Rider in the Agents of S.H.I.E.L.D. season four finale promises to be something to remember.
Agents of S.H.I.E.L.D. season 4 concludes Tuesday, May 16 with ‘World’s End’ at 10pm on ABC.