Path of the Inner Demon

This barbarian path is less an option that's chosen, and is instead one forced upon some. An inner demon resides within these barbarians, a being of pure hatred and fury who's existence stems from pain and misery, and who now, in the face of the dangers and magics of adventuring life, is beginning to come to the surface.

When you rage, an innermost monster is let out. To others, it looks like you just enter a blind rage, but to yourself and those with the ability to see things for how they truly are, you transform into the manifestation of your inner demon. Decide what your inner demon looks like and how this being came to be, or roll on the origins table to determine it.

1.  I encountered a fiend in my youth. Everyone thought i escaped unharmed, but i still feel it inside.
2. I had an imaginary friend, but they didn't want to go away when I grew up.
3. Untamed magic did something to me. Something that changed who I am inside.
4. I suffered something traumatizing in my youth, and that trauma took the form of something monstrous.
5. A magic user cursed me, and now that curse manifests in my rage.
6. A vengeful spirit haunts me, and its influence takes on this form.

Ungodly Strength

3rd level inner demon feature

Your inner demon's strength manifests in reality when you rage. Your unarmed attacks can now deal 1d8 bludgeoning or slashing damage, which becomes 1d10 at 10th level, and 1d12 at 14th level. These attacks count as magical for the purposes of overcoming nonmagical damage resistances.

To normal eyes, these attacks appear to just be you pummeling enemies with your bare hands, or slashing at them with claws or nails.

The Horror Inside

6th level inner demon feature

The horrific nature of the inner demon grants you proficiency in intimidation, and releasing it lets you attempt to frighten any enemy creature within 30 feet. Each creature affected has to make a wisdom saving throw with the DC of 8 + Your proficiency bonus + your strength modifier.

You also gain the option to attempt to frighten enemies within 30 feet you can see as an action when your not raging, the creatures must make a wisdom saving throw, DC 8 + your proficiency bonus + your charisma modifier. Every time its their turn, the frightened can reattempt the wisdom saving throw. If they have disadvantage on the first save, that remains as long as you remain in sight.

If targets save, they are unable to be frightened by it for 24 hours.

Hellish Willpower

10th level Inner Demon feature

The inner demon's relentless willpower seeps into reality.

While raging, you are immune to being frightened or charmed

You also gain the ability to end one negative condition affecting you as a reaction. You can use this feature an equal number of times to your proficiency modifier, and regain all expended uses on a long rest.

Cornered Prey

10th level Inner Demon feature

Your enemies terror spurns your bloodlust onward. When enemies are frightened of you (be it from The Horror Inside, or something else) you deal 2d8 + your proficiency modifier to them as bonus damage. This upgrades to 2d10 + your proficiency modifier at 14th level.

Unrelenting Chase

14th level Inner Demon feature 

The bloodlust of the inner demon enhances your movement, compelling you forward and enhancing your speed. You gain 20 extra feet of movement speed, and it costs no extra movement speed to move across difficult terrain.

In addition, when a hostile creature moves out of your range, you can move up to your movement speed towards it, and use a reaction to make two attacks of opportunity.