In what was generally considered to be a very strong run, the addition of Ghost Rider was a particular highlight of Agents of S.H.I.E.L.D.'s fourth season. Gabriel Luna's interpretation of Robbie Reyes finally did justice to one of Marvel's most loved comic characters and added a familiar face - well, flaming skull - to a show that has largely dealt with lesser-known superheroes.

In the climax of season four's first arc, Reyes and the Ghost Rider sacrificed themselves by dragging Reyes' Uncle Eli to another dimension after the former jailbird used the power of the Darkhold to imbue himself with God-like abilities, and was threatening to cause devastation of a massive scale. Happily, Reyes' departure wasn't permanent and the character returned in season finale 'World's End' to take down AIDA, stop her evil schemes and return the Darkhold to where it came from.

Characters are rarely truly gone in Agents of S.H.I.E.L.D. - just ask Trip and Ward, who returned in the recent Framework arc - and the popularity of both Ghost Rider and Luna's version of the character will surely mean that a return in season five is firmly on the table. It's worth keeping in mind that rumors of a Ghost Rider spinoff series have been doing the rounds and if these eventually came to fruition, it could spell the end for the character's tenure on Agents of S.H.I.E.L.D. Until such plans are confirmed, however, Ghost Rider remains a key player in the show's current arsenal of characters and would be a welcome element next season. But what exactly could be in store for Robbie Reyes in season five?

'World's End' gave viewers two huge lingering plot threads to chew over between seasons and at least one of them, if not both, has Ghost Rider at the center. The first of these Clark Gregg is probably still pinching himself about; Reyes transferred the Ghost Rider power over to Phil Coulson in order to launch a sneak attack on AIDA. As much as the scene appealed to the audience's inner geek, the show-runners have since confirmed that this transaction came at a price. The Ghost Rider can't simply be tossed around from person to person with no consequences and Coulson had to strike a deal with the demon in order to make the switch.

Details of said deal are currently very much unknown but Reyes telling Coulson he didn't envy him before departing is a strong indication that the price Phil paid must've been high. Naturally, this story could easily play out without an appearance from Ghost Rider himself and season five might simply see Coulson succumb to whatever torment he is destined to face without any interference from the being that caused it. However, the unconfirmed details of Coulson and Ghost Rider's deal does give Agents of S.H.I.E.L.D. a ready-made route to re-introduce Reyes next season. For example, the S.H.I.E.L.D. team may summon Reyes in an attempt to help Coulson break free from whatever trouble he faces. Alternatively, Ghost Rider could return to collect whatever price was promised to him, with Reyes unwillingly facing off against his S.H.I.E.L.D. pals.

The other big cliffhanger was the fact that the team ended the episode in space, courtesy of some enigmatic captors. This revelation may be somehow linked to Coulson's deal with Ghost Rider but it's far more likely to simply be the start of a brand new story-line for next season. If so, this would perhaps indicate that any appearance of Ghost Rider will occur at a later point in the next series, after the intergalactic material has been fully explored and dealt with. After all, it would be meaningless for Reyes to come to bail the S.H.I.E.L.D. team out after he did exactly that with AIDA in the season four finale. Coulson and co. need to solve this new problem themselves.

The Other Dimension

The Darkhold in Agents of SHIELD season 4

Those theories largely work on the assumption that any appearance of Ghost Rider in season five will be alongside the other primary members of the cast but there is an attractive other option. 'World's End' saw Reyes return to an alternate dimension with the Darkhold in hand, claiming to be taking the evil book back to where it came from. Reyes also made several other comments regarding his time in this other dimension, stating that Ghost Rider is permanently in charge over there, spending most of his time fighting and killing. It was also heavily hinted that Ghost Rider shared an innate connection with the power of the Darkhold since both the demon and the book boast the same place of origin.

Ghost Rider's adventures in this mysterious other dimension could be an immensely interesting concept to explore in season five as a B-plot, perhaps going into more detail about the origins of both the flaming skull and the Darkhold. Although such a story line would likely be a hugely successful addition to Agents of S.H.I.E.L.D., it would also act as the perfect set-up for a potential Ghost Rider spinoff series and if such a project does see the light of day, the demon's origins will surely be saved for that venture.

There is, however, one plot thread still tying Ghost Rider to Earth that could definitely feature in season five: the teased romance between Robbie Reyes and Daisy Johnson. Daisy has had a tough time with men throughout Agents of S.H.I.E.L.D. and dating a man with an angry flaming skull inside him isn't going to help buck that trend. Nevertheless, the season four finale dropped the strongest hints yet that there is something romantic between the duo, as they shared a lingering glance before Reyes returned to Ghost Rider's native dimension. These seeds will surely bloom at some point and with Daisy changing love interests roughly every two seasons, next year could certainly see Quake and Ghost Rider finally hook up.

Whether it's romance, a solo adventure in an alternate dimension or continued collusion with the S.H.I.E.L.D. team, there's no doubt that fans will be hoping for a Ghost Rider return in season five given the quality supernatural ass-kicking he brought to the most recent run of episodes. A potential spinoff series could jeopardize the character's continued presence in Agents of S.H.I.E.L.D. but at least the show has left the door firmly open, learning from the mistake made with Bobbi and Hunter - two popular characters who were written out of the show for the purposes of a spinoff that never got further than a pilot episode. One thing is for sure though, the Marvel Cinematic Universe isn't done with Ghost Rider yet.

Next: Agents of SHIELD Season 5 Premieres in January 2018 With No Breaks

Agents of S.H.I.E.L.D. season five premieres in January 2018 on ABC.