Path of Rectitude

the Path of Rectitude entails barbarians whose rage is born through a multitude of things such as injustice, grief, suffering and pressure, continuously building up and needing to learn to control it as the stress was so volatile and quick to accumulate that it could spiral out of control very easily if not careful, forcing them to learn to suppress and control their emotions whether they like it or not both for their own good and for that of those around; or, in the case of having no one by their side, for their own good 

this made the user's body learn to subconsciously conserve energy for situations when it's really needed, suppressing their capabilities while at the same time the user's mental resilience would have gained a massive increase, however in spite of their resilience they remained emotional and easily affected by things going on around them, in some cases extremely empathetic, making them a bit emotionally unstable 

additionally, people of this path are fueled by pain and exhaustion, being capable of continuously pushing and doing things that they would otherwise not be able to do without passing a certain cooldown or resting in exchange of causing themselves to suffer, pushing further than most in exchange of harming themselves and exhausting themselves further 

and, unlike the normal barbarian's, their rage is a lot more difficult to trigger, yet in spite of this once it does trigger it never disappears until something calms them down, this rage often being fuelled by a desire to right the wrong much like justice or vengeance, except focused on desire instead of justice system 

Reactive Will

90% resistance to all mental effects; additionally takes an additional -50% less damage from psychic attacks that do affect them 
nearly unable to resist charm; may be able to become conflicted but will not be capable of having any ill or negative intention or thought towards the one charming them. this effect immediately expires once the charmer tries to harm them or someone the user cares about 
if the one charming them gathers their trust over extended periods of time the user will be unable to defy them as long as what they ask for doesn't go against the user's goals 

you may also be capable of using spells while in rage mode; keep note that while this subclass may be able to use spells, it cannot start with them; it must learn them from scratch during the campaign or be taught by others 

Energy Conservation

your STR & CON are always halved no matter the situation, however at 80% hp the drawback gets reduced to 25% and you gain a +1 modifier to all damage and survival throws, and at 50% hp your STR & CON are back to normal and a +5 modifier to all damage and survival throws 

once your hp drops to 50% you will gain a 1% bonus to STR, DEX & CON for each 1% lost, up to a maximum of 50% and you will fall under the fatigued state 

Endless Fury

the user cannot trigger rage against good actions, but when it does trigger the user can continue to use it past it's cooldown 
once the user becomes fatigued and each time the rage is supposed to go out the user will lose 1 CON but gain 1 STR & DEX; when revived/healed from near death recover 5 lost CON and lose 2 STR & DEX; if you reach 1 CON you cannot be revived or healed for 1 turn and must make a death saving throw 
at level 20 you will instead gain 1 STR and lose 1 DEX each 2 turns and gain 1 STR & 1 DEX every time you're healed or hit 

the user may be capable of enduring 1 life threatening hit at the cost of losing 4 CON and gaining 5 STR 
at level 15 lose 2 CON and gain 4 STR instead 

after taking 2 long rests the user's stats will return back to normal 

Subconscious Desire

towards acts of pure evil or when your hp reaches 5% you may be capable of losing access to all rage modifiers and abilities, in exchange gaining +10 to all STR, DEX & WIS rolls 

upon reaching level 20 you will no longer suffer exhaustion from rage and will be capable of using it's modifiers along with Subconscious Desire; however, the STR, DEX & WIS rolls will instead have a +5