WARNING: The following contains spoilers for Immortal Hulk #45 by Al Ewing, Joe Bennett, Ruy José, Belardino Brabo, Paul Mounts and VC's Cory Petit on sale now.
The Hulk's powers have manifested themselves in a variety of other gamma creatures over the years. These various Hulks usually inherit the same strength and uncontrollable rage as Bruce Banner. Marvel's newest gamma mutate, Jackie McGee, just inherited the Hulk's ability to see ghosts.
Jackie's latest power-set is elaborated upon in Immortal Hulk #45, by Al Ewing and Joe Bennett. In New Mexico, Jackie and Shaman can see through her eyes and are tracking Rick Jones and another person's spirit inside of Rick's body. Additionally, Jackie also sees several gamma demons floating around Rick's body.
Shaman explains to Jackie that these "fauna" exist outside of the space perceived by human eyes. These creatures could be seen as astral projections or similar beings. Simply put, Jackie can see ghosts, which Puck points out as a Hulk power. Puck notes how Jackie could probably smell lies too, as the two abilities are connected. Jackie has had the ability to track gamma signatures and see gamma spirits since Immortal Hulk #42, by Al Ewing, Alex Lins, Adam Gorham, Rachael Stott and Joe Bennett. Now, it seems that Jackie is gaining a better understanding of these useful powers.
In the past, the Hulk has been able to see ghosts, a power that has helped The Jade Giant. For one thing, the Hulk has shown that he can see and hear Doctor Strange's astral form. This ability has helped the Hulk during his many team-ups with Doctor Strange, both on the Defenders and outside of this team.
The Green Goliath has also occasionally seen the ghost of his father, Brian Banner. Bruce's father has tormented the Hulk to no end, showing that the Hulk's power to see ghosts is both a blessing and a curse. The power to smell lies, however, is a fairly new ability.
Ever since Immortal Hulk #1, by Al Ewing and Joe Bennett, the Hulk has claimed that he can smell liars. In doing so, the Hulk has been able to torment and punish others for their sins. This ability is quite similar to Hulk's ghost vision, since both involve sensing truth in the world. In this way, the Hulk always knows who is present and what's inside someone's soul.
Both Hulk's ability to see ghosts and to smell lies are very relevant to the current Immortal Hulk series. Immortal Hulk is a horror series, involving a Hell-like realm called the Below-Place, moments of body horror and many different types of gamma monsters. It's only fitting that gamma ghosts are part of this tableau of nightmares.
It's quite useful to track gamma creatures who are both corporeal and incorporeal since the Below-Place has produced plenty of these monsters. By seeing these gamma "fauna," people like Jackie can see how the Below-Place is seeping into the world. This way, Jackie and others can gain a better understanding of the Below-Place and its effects outside of this realm.
Moreover, considering the number of body swaps that have taken place recently, it's important to smell the truth and see who is truly inside the body of a gamma mutate. For example, Hulk was able to see Brian Banner's ghost inside of Sasquatch, while Jackie McGee could see Doc Samson in the Sasquatch's body later on.
By detecting the true essence of these gamma creatures, Jackie and the Hulk can tell who's who. This ability is very important in a series where people keep jumping from one body to another, thanks to the power of the Green Door. Puck makes a good point when he says that smelling lies is a good power for Jackie as a reporter.
Jackie has spent years trying to get to the truth of important events involving the Hulk. By seeing everyone who is really present and smelling their lies, Jackie can discern what's actually going on. As these powers develop, Jackie might be important to stopping villains like the Leader. Furthermore, Jackie has said that she wants to be like the Hulk. With her new powers, Jackie can finally see the world in an honest yet horrific light, just like Bruce Banner.