堕天使

Missing, extremely new, or very obvious to obtain.

Fallen angels are typically beings that were once pure or divine but has fallen from grace, often through them deceiving or betraying their creator/leader. Both the Trailblazer and Xunsang can be seen as fallen angels, where the former, with good intentions, is tricked into a scam (which represents their fall from grace), while the latter's participation in deceipt, whether willingly or as a victim herself if her sob story is true, marks her own fall from grace, since Xunsang must deceive others.