WARNING: The following contains major spoilers for DC Horror Presents: The Conjuring: The Lover #4, available now from DC Comics.
In The Conjuring: The Devil Made Me Do It, one of the core mysteries being investigated by the Warrens focuses on young Jessica, who apparently turned into a slasher and murdered her best friend, Katie. The paranormal experts tracked the incident to Boston, intrigued since there was a connection to the Occultist they were chasing in the present. Even though the movie did reveal key insight into Jess killing her friend, it left some serious questions about why she did that. But in David L. Johnson-McGoldrick, Rex Ogle, Garry Brown, Mike Spicer and Becca Carey's The Conjuring: The Lover #4, a massive murder mystery is finally solved, and it's quite heartbreaking.
The Warrens felt that a demon may have possessed Jess to sacrifice Katie, probably to offer up souls to the devil based on the Occultist's big plan. We did know the villain goaded Jess to jump off the cliff in the nearby woods, but there was a slight discrepancy as it wasn't known for sure if anything satanic was in Jess.
Now, we learn she wasn't possessed; she was mentally manipulated. This issue reveals more as we see Jess being kicked out of university after the Occultist made her hallucinate that, Kyle (a guy who liked her), was her demonic-looking self. This caused Jess to push Kyle in front a bus, which got her expelled.
While Jess thought the root of these was shame over her sexuality, it seems like this is the Occultist opening the doorway for possession. More of these hallucinations occur at home as Jess' mom chides her for her actions. Jess is left screaming from more visions with the Occultist as well, but luckily her dad is there to comfort her. Realizing she loves and misses Katie, he urges her to go meet her bestie to regain her sanity. That's how they ended up in the forest in the movie, as we see Jess giving Katie a bracelet like what they made for each other when they were kids. Jess confirms she never took off the one Katie got her, resulting in them kissing. It's Jess' dream come true and something totally left out of the movie, but things go from romantic to horrific when Jess has to break the lip-lock.
It's because she sees the Occultist ready to attack her, which causes her to draw the knife she brought for protection. Sadly, Jess thinks the Occultist shape-shifted into Katie and is enraged, telling her she's comfortable in her own skin now and no longer afraid of being lesbian. Her dad's subliminal support has emboldened her and Jess stabs her up.
Sadly, the spell is broken right after and Jess sees what she's done: leaving Katie bleeding out, dying and asking why. This sends a bloody Jess screaming in the woods, offering much more context to Lorraine's vision as the soulmates meet an unfortunate ending.