The worst is yet to come for Jace, just when we thought that he could finally breathe a sigh of relief following Valentine’s death. It does not get any better for the Shadowhunter in season 3 with the arrival of the demon Lilith.

Jace went through a lot in the past two seasons of the Freeform series. He battled demons, faced the ire of the Downworlders (after he activated the Soul Sword), and was stabbed by Jonathan. Even worse, he died.

To recap: In the Season 2 finale Valentine surprised Jace and Clary when they arrived at Lake Lynn in an attempt to stop him from raising the angel Raziel.

Valentine stabbed Jace and used his angel blood to awaken Raziel. Valentine asked for the destruction of all Downworlders but the angel declined. Clary and his father got into a fight and she stabbed him several times, which killed him. Raziel gave Clary one wish and she asked that Jace live again. So what could be worse than dying? It seems the arrival of the demon Lilith is bad news for the Shadowhunters, especially for Jace.

Lilith’s debut

The demon appeared in the Season 2 finale of the “Shadowhunters.” Jonathan summoned her in his dying breath. We saw how she formed when the wights came together. She appeared inside the cave with the dead Jonathan, whom she called her “son.”

Who is Lilith in the Shadowhunters story?

In Cassandra Clare’s “Mortal Instruments” books (which the show is based on), Lilith is a Greater Demon whom Valentine once summoned.

He asked to use her blood for his experiments to which she agreed. Valentine used her blood on his unborn son through his wife Jocelyn. This son is Jonathan, who we saw masquerade as Sebastian in the “Shadowhunters” Season 2.

Why is Lilith dangerous for Jace?

In the fourth book “City of Fallen Angels,” Jace becomes vulnerable to demonic influences because he was reborn.

This gave Lilith control over his mind. She is able to send him dark dreams, especially one of him killing Clary. She also influences him to do evil things.

Interestingly, the “Shadowhunters” Season 3 is based on “City of Fallen Angels” and Lilith is the new Big Bad. It is safe to say then that what Jace experienced in the Season 2 finale is Lilith’s doing.

We saw him weaken by an unseen force about the same time that the demon appeared.

Who plays Lilith in the 'Shadowhunters' Season 3?

Executive producer Todd Slavkin confirmed in a tweet that Lilith has been cast. However, he did not say who will play the character. According to Cartermatt, there is no rush to reveal the actress as the new season does not air until January 2018.