The Flash: Repentance

After defeating Wells for good, Barry reunites with Caitlin and Cisco, reforming team Flash.
His newfound relationship with a certain magnetic young female Metahuman is blooming and all looks right in the world for our Hero.
But a series of mysterious deaths keeps CCPD and it's forensic scientists at a loss.
A villain, plagued by demons and decisions made in his past isn't like anything they have encountered before.
Who is he, and why does he hate Barry Allen?

This story is a continuance from my previous story "Lost".
It can be read as a separate story, but for the introduction to my original character Wenn, and events that are linked in this story, I recommend reading that story first.
Contains a very graphic (read sex) chapter, chapter VII. Don't like, don't read.