D&D 5E Good disadvantage for missing heart?

[Tormyr]

I would also recommend the TV show Once Upon a Time as inspiration for this. In the show, magic users can rip out/put back someone's heart. The heart appears as a fist sized gem that is ruby for a good person and black for an evil person. When the heart is out, several things happen:
The victim has reduced emotion/empathy.
The holder of the heart can listen in on the victim.
The holder can speak through the victim using the victim's voice.
The holder can control the victim.
The holder can torture the victim by squeezing the heart.
The holder can kill the victim by crushing the heart.

 

[jasper]

I stealing from everyone.
Disadvantage on death saves. And Cha checks
Advantage on int checks.
Let her chose one Immunity charm or fear. You choose a vulnerabilitiy

 

[Jester David]

I like the emotionless aspect. That's handy and cool. It should be charmed as you're less subject to being influenced that frightened, as fear is much more primal than compassion. Fight or flight and such.
I disagree that you should be easier to kill, as you're life is literally sitting in someone else's hands. That's almost another benefit. But you could heal more slowly, as some of your life force is outside you body.

Benefit: Immune to being charmed. When you make a death saving throw and roll a 5 to 9, you can instead treat that as a 10.
Weakness: -5 on Wisdom (Insight) and Charisma (Persuasion) checks. Reduce Hit Dice by 1 (Or half proficiency bonus?).
Flaw: "I have trouble sensing the emotions of others."

Is it balanced? Nope. But it doesn't need to be. It's a cool boon that's awarded. It's not a feat or character option. And if it's too good, you can also choose to remove it easily enough. Plus, over time it could get worse. Really, it should get worse. Perhaps the PC becomes insensitive and uncaring, with the flaw increasing and they automatically fail Insight and Persuasion checks. The penalty might begin to apply to Handle Animal.