Curse of Blood Mania

Your ego has been overtaken by a psychotic, blood-crazed alter-ego.  The alter-ego is driven by a rabid blood lust and speaks only madness, either with nonsensical cryptic metaphors or explicit threats of egregious violence.  Your ego remains as a forced spectator to your alter-ego's actions, but you retain limited influence over the alter-ego's behavior, allowing you to 'steer' them from harming certain individuals.  This might be accomplished by telling your alter-ego that they will find more blood by working with others than being alone.  The alter-ego is clearly distressed by your restrictions and resentfully refers to you as the voice in their head.

The nature of your madness confers the following effects and abilities:

• As a reaction, you can attempt to wrestle back control from the alter-ego.  Roll a d20 and add your proficiency bonus.  On a result of 20 or higher, you regain control of your body for 1d6 x 6 seconds.  During that time, the effects of this curse no longer apply.  Once you have attempted this, you must finish a long rest until you can do so again.  You can take this reaction at any time, the trigger condition is whenever the suppressed ego decides it would be advantageous.  
• You have disadvantage on Charisma, Intelligence, and Wisdom saving throws.
• You have disadvantage on ability checks that use Charisma, Intelligence, or Wisdom, with the exception of Perception (Wisdom) checks and Intimidation (Charisma) checks.
• You gain proficiency in the Intimidation skill.  If you are already proficient in Intimidation, you gain Expertise, as a Bard or Rogue might.
• You have advantage on Intimidation checks against creatures who are not larger than you.
• You are immune to being frightened.
• As a bonus action on each of your turns, you can make an uncannily threatening remark towards a creature you can see.  If the target can hear and understand you, it must succeed on a Wisdom saving throw against a DC of 8 + your proficiency bonus or be frightened of you until the end of its next turn.  On a success, the creature becomes immune to this effect until it sees you kill another creature or use an Action to mutilate a corpse.

A horrific curse of unknown origin, most individuals succumb completely to the madness after a time. The task of preventing one's insane self from harming the innocent is an unending burden, and it only grows easier to give up and let fate take its course with each passing day.  Those with an iron-clad will, such as yourself, can manage not only to keep themselves in check but steer their vicious inclinations towards a greater cause.