You have become two halves of a whole with your pet companion, allowing you to not only inspire each other, but to grow together and become far stronger then you ever could alone.  You have learned to become one with your companion, giving you the option to fight with them as a animal-like combatant, or helping your partner to fight.

Leader of the Pack

At 3rd level, you gain a beast companion that accompanies you on your adventures and is trained to fight alongside you. Choose a beast that is no larger than Large and that has a challenge rating of 1 or lower. . The following numbers increase by 1 when your proficiency bonus increases by 1: the companion’s skill and saving throw bonuses and the bonuses to hit and damage of its rend attack. This also increases its AC each time by 1.  Its hit point maximum is treated like your own. When you level, your companion levels, using the die rolled for its health to add maximum hit points.  For example, a Brown Bear's hit points are determined by rolling a D10.  This would mean every level you would roll a D10 plus its constitution modifier, like a player's level up. 

The beast obeys your commands as best as it can. It takes its actions on your turn. On your turn, you can verbally command the beast where to move (no action required by you). You can use your bonus action to verbally command it to take the Attack action or the Dash, Disengage, or Help action as your action. If you don't issue a command, the beast takes the Dodge action. 

Your companion gains multiple abilities in addition to those stated above.  When you and your companion are both within melee distance of an opponent, your pet has advantage on its attacks.  If you and your companion make attacks on the same target on your turn, you add your Wrath of the Pack die to your attack (see Wrath of the Pack).  

Your connection with your companion allows you to cast touch spells through your companion.  

If you are incapacitated or absent, the beast acts on its own, focusing on protecting you and itself. The beast never requires your command to use its reaction, such as when making an opportunity attack.

While traveling through your favored terrain with only the beast, you can move stealthily at a normal pace.

If the beast dies, you can obtain a new companion by spending 8 hours magically bonding with a beast that isn’t hostile to you and that meets the requirements.

Wrath of the Pack

When you and your companion fight together, you both create new opportunities and manage to take advantage of openings easier, leading to more damage to your target.  

When you and your companion both make melee attacks against the same target, you add additional damage to your attack as you hit more vital locations in your hunt.  the additional damage die increases as you and your companion level, perfecting your teamwork and hunting.  

Starting at third level, you gain 1d4 additional damage to your companion's attacks if your companion attacked the same target as you.  This damage increases to 1d6 at fifth level, 1d8 at tenth level, 1d10 at fifteenth level.  

This may only happen once per pair of attacks (one from you and one from your companion).  

Soul Binding

Beginning at 7th level, your companion adapts a danger sense centered around you.  As your companion's reaction, if your companion is with 5 ft of you, it may take a single blow for you, protecting you from damage. The damage taken bypasses all resistances your companion might have, as it throws itself in the way of the damage with no regard for itself.  

In addition, the beast's attacks now count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

Unbridled Aggression

Starting at 11th level, your companion can either make two attacks or take the Multi-attack action if it has it.  If your companions Multi-attack action gives it more then two attacks, it may only make two attacks.  

 

Unending Loyalty

Beginning at 15th level, when you cast a spell targeting yourself, you can also affect your beast companion with the spell if the beast is within 30 feet of you.  

When either you or your companion is knocked unconscious, the other is granted the following abilities:

Reckless Abandon- You gain 10ft of movement, and advantage on attack rolls.  You or your companion is able to use your Wrath of the Pack die, without the unconscious partner within range.  You or your companion (whichever is conscious) takes a -2 AC penalty from flying into a rage, throwing caution to the wind.  If your Partner dies permanently, you may use the same resurrection rules for a character (at DM's discretion) for your companion.  You lose all Animal Soul benefits after the combat in which your companion has died until you resurrect or gain a new companion.  If you gain a new companion, you gain one class ability (in order) back per day with your new companion until you have achieved the same bond. 

 

This can be extended or taken out by Dm's choice.  DM can also choose to decrease Wrath of the Pack die by one die for a period of time to represent the bond being built.