A través de la oscuridad (2022)

Both dramas are about profiling.
Both are taking place in various time zones starting from the 80ties to the 2000s.
Both are thrillers with interesting cases. Both form teams that specialize in this.
And both have a male lead that is shaped due to his childhood and is doing a sort of narrative analysis's throughout the episodes.

Both "Black: I Saw the Devil" and "Through the Darkness" are about criminal profiling. They analyse several cases to better understand the mind of the criminal.
However, "Black" is not a drama, but a TV show.
The methods they work with are also different. In Through the Darkness the profiler analyses the criminals mainly by interviewing them. While in Black they analyse letters from the criminals, past interviews and reenactments of the cases.

Both dramas are about crime and criminal investigations. In both viewers can observe the behaviour of criminals.

In both, the profiler plays an effective role in discovering the truth through the analysis of criminal psychology and examining the role of the environment in criminal behaviour.
In both, the viewer closely observes the criminal's daily life and behaviours.

Both lead characters have sullen and serious personalities who seem to have decided to focus on their career than look for romantic relationships. Also, both lead characters deal with the "dark" side, though from completely different angles.