Both BL dramas take place in a medical environment and include criminal investigation.
They are based on a novel of the same writer and both are supposed to be sequels of Manner of Death.
Same director and screenwriter. Both share the premise of an inspector investigating a series of serial killings with his lover being a prime suspect in the murder cases.
Both Dear Doctor, I’m Coming for Soul and Spare Me Your Mercy are Thai LGBT / BL Dramas that have a doctor as one of the main lead characters. Both deal with death in their primary story line.