Beast Barbarian

Beast companion Subclass(must have animal companion to use effects of subclass): when you choose this class your animal companion rages when the player does and the death of your animal companion triggers ability (rage to fight loss) with the following effects until companion is revived or new animal companion is acquired: player gains resistance to whatever damage type killed companion and gains +3 to damage modifier and becomes enraged till player decides to calm or sleep.

Enduring. Your companion gains +1 HP per companion level.

Player has advantage on animal handling checks with animal companion and +3 to animal handling checks with animal companion when not raging

Reaction: when animal companion is attacked by an enemy in your melee range you take an attack on them up to twice per long rest.

Reaction: when player is attacked by enemy that’s within range of animal companion, animal companion will take an attack up to twice per long rest.

Beast bond

at 3rd level your animal companion gains proficiency in medium armor and +1 to dexterity modifier, player gains +1 to dexterity player chooses 1 damage type to gain resistance to. Player also grains effect When separated from animal companion by any involuntary means the ability searching defender activates causing the following effects: player gains extra attack action and resistance to 1 damage type of player’s choosing for 1 hour but takes[condition][exhaustion][condition] at the end of said hour. 

• Territorial. Other creatures provoke an opportunity attack from your companion when they enter your companion's reach.
• Punishing. When your companion takes the Dodge action, if they are the target of a melee attack they can make an attack against that target as a reaction.
• when Raging

• Animal companion has advantage on Strength checks and Strength saving throws.

  • When animal companion makes an attack using Strength, they gain a bonus to the damage roll that increases as player gains levels as a barbarian, as shown in the Rage Damage column of the Barbarian table.
  • Animal companion has resistance to bludgeoning, piercing, and slashing damage

Beastial rage

At 6th level When raging, player gains resistance to fire and necrotic damage spreading to companion when 15ft from animal companion.

• Natural armor: gains +1 to Ac.
• Can use Feat to enhance Animal companion, How is up to DMs discretion.

War Beast

At 10th level player gains attack dramatic swing: (2d8+4) and companion can perform attack viscous bite: (1d12+2) twice a day per long rest as an attack action, your animal companion also gains +1 to damage modifier and +1 to AC.

• Precise. Your Companion's attacks have +2 to hit
• Ferocious. Your companion's attacks have +1 to damage rolls

• Uncanny Dodge. When an attacker that your companion can see hits them with an Attack, they can use their reaction to halve the attack’s damage against them.

 

Apex Pack

At 14th level player gains resistance to lightning damage while your animal companion gains  and gives player +1 to perception saving throws.

Now you have mastered your bond with your companion. As long as they can see you, your companion has advantage on saving throws against fear and being charmed. 

player and their companion gain a +2 to dexterity and strength