Try Interview with a Murderer and Black Mirror
Also Hotel Phryne and Nevermore
Try the beast must die
You can try this tag search, or use your own tag https://www.mangago.zone/tag/horror%20BL/
This manhua https://www.mangago.zone/read-manga/copper_coins/
is adapted from an incredibly well written novel of the same name https://www.novelupdates.com/series/copper-coins/
It's a very moving story! That author is perfection!
Looking for anything psychological, thriller, or horror, preferably BL/shounen ai