I was reading the description of Book 10 on Waterstones.com, and in the description it said that Bec and Lord Loss formed an alliance.
Here's the description:
The final dramatic conclusion to Darren Shan's international phenomena, The Demonata.
Expect the unexpected..."The girl gazes up at me. She's even younger than I thought, clutching a small teddy bear in one hand. 'Are you the bogey man?' she whispers, eyes round. 'Yes,' I croak, then take hold of her head with my huge, scarred, blood-soaked hands and crush..."
Beranabus and Dervish are gone. Bec has formed an unholy alliance with Lord Loss. Kernel is blind, held on Earth against his will. Grubbs is mad with grief and spinning out of control. The demons are crossing. The Disciples are falling. The Shadow is waiting. Welcome to the end.
Do you think that Bec is just going undercover or something to destroy the Shadow/Lord Loss secretly?