*psychological

Rather dark psychological but not totally
this mystery includes:
strange family history, memory loss, coping with death, wanting to die, unable to die, immortality?, obsessions

Despite such a heavy topic, this manga's main vampire Bloody is can be rather cute and light hearted at times.

This is tagged shoujo due to being released in a shoujo magazine.
But I really with this was Shounen Ai

a little bit dark/twisted psychological manga but not that much
Protagonist body swaps with a kid who tried to commit suicide.
includes:
two face people, school bullying, blackmail, dealing with someone he knew before he swapped bodies, sad pasts, family abuse, strange family situations

end up strangely liking the 2 main characters. love their interactions with each other.
*Shouen Ai*

only a little psychological/not that dark.(probably the least dark on this list)
This is more like a shoujo yaoi. Deals with relationships.
some people are purposely trying to mess with others and their relationships.
includes:
devils and angles, age gaps, discrimination/bullying
*Yaoi warning*

About a boy whose blood regenerates fast and a vampire
includes:
strange/sad family situation, abuse/using, secrets/blackmail, purposely making misunderstandings
A little sad but very interesting
*Yaoi warning*

More sad psychological than dark/twisted psychological.
About a "Royal Blood" who despises "servants"
includes:
interesting/twisted pasts, family is killed, trust issues, abuse/confinement, wanting to forget, forgetting
*Yaoi warning*

Not Dark/twisted just psychological
About a man trying to help cure a mysophobic secretary
includes:
Mysophobia(fear of germs), trust issues, past plays a role
*Yaoi warning*

A little dark psychological
about a man taking back his family's thone and a boy from the enemies' family who was reduced to a slave
includes:
betrayal, hostages, families are enemies, spies, poison,
despite the dark psychological, this manga is more of a love story
*Yaoi warning*

only a little psychological-not dark
this manga is more light hearted and funny
about an average guy who runs a hot blog about high heels and a once famous shoe maker

includes:
coping after betrayal, famed, obsession, secrets, blackmail, past plays a role

a little dark/twisted psychological
at time is rather light hearted and funny
about the Noblesse (the being that watches over vampires)
includes:
human experiments(and other races), killing, lies, death, secrets, using, different mindsets, betrayal, past plays a role
age difference-humans, vampires, werewolves
despite the darkness and psychological traits, this manga is very interesting in a non-dark/twisted way

Very intense/action packed love story
includes:
assassination, memory loss, betrayal, PSTD, framing, trust issues, kidnapping, blackmail