The midseason finale of "Arrow" Season 5 left a lot of cliffhangers to look forward to in the next year, but at the same time, it left a lot of heartbreak to mend over the break.

In the midseason finale, titled "What We Leave Behind," Prometheus attacks Curtis after a Christmas party. Doctors then discover a drug tied to Oliver's former target, pharmaceutical CEO Justin Claybourne, who released a strain of tuberculosis and increased the price of the sole medicine that would cure it.

Oliver now suspects that his son might be Prometheus. Felicity's boyfriend, Billy, is captured while tracking Prometheus. When Oliver tracks Prometheus, he throws arrows into a costume he believes to be the villain. It turns out the costumed man was Billy, and Oliver has killed him.

Billy's death could lead Felicity spiraling down when we see her again in "Arrow" Season 5. Showrunner Marc Guggenheim teased that Emily Bett Rickard's character will head down a "dark" path.

"One thing Felicity is not going to do, I can tell you for sure, is blame Oliver. She recognizes the manipulations that have led to this situation," showrunner Wendy Mericle tells TVLine about Billy's death. "Her heart is broken in that last moment for Oliver and for Malone and for herself."

One of the repercussions of Billy's death is that Felicity will focus on Prometheus and directing all her anger at pinning him down. This will take her to a much darker place and would cause her to be more detached from Team Arrow. Her dangerous and highly ambitious mission will lead her to people from her past that can also help her with this new path that she's contemplating.

Another big surprise in "Arrow" Season 5 midseason finale is Oliver's discovery that Laurel Lance is still very much alive. However, Stephen Amell tells Cinema Blend that viewers have to tune in because they still have to ascertain if this is really the Laurel they once knew, given all the peculiar things that has happened on the show.

In recall, Laurel was killed in "Arrow" Season 4 by Damien Dahrk and it was said that she was dead for real. This may be the real Laurel or a doppleganger from another Earth.

"Arrow" Season 5 returns to The CW on Jan. 18, 2017.