This is part of a 3-part system for a born lycanthrope character build.  You need the background, feat and Magic item to add to your character to enable all features.

The spawn of either a human and a lycanthrope or two lycanthropes, you are touched forever by the beast blood. While you have the ability to control your transformations, your human form is forever changed after your first transformation as a young child.  You have built a resistant to all forms of non-magical physical damage but are vulnerable to silvered weapons in all forms.  Moreso, you have advantage on Perception and Intimidation rolls. 

In human form, your teeth are pointed, requiring a meat only diet.  Your nails always are closer to claws.  Your ears appear more Elven to help with your hearing. Your unarmed attacks now provide a 1d4+1 damage vs a base 1+strength modifier.   

Transformations gain you great size and strength, but you must maintain control of your anger, lest you lose yourself to your bloodlust.

In the Hybrid form you grow to roughly 8 or 9 feet tall and cannot communicate verbally. Your Strength temporarily increases by 2, your speed increases to 40ft, your hit point maximum is increased by 11 (2d10) temporarily (you will have to physically add at each transformation), and you gain an additional attack action.  You cannot use armor, but you are capable of using most melee weapons.  Your AC increases by 1, claw attacks provide a 2d4+2, and bite attacks provide 1d8+2 damage.  A non-lycanthrope humanoid hit by a bite attack from a creature that carries the curse of lycanthropy must succeed on a constitution saving throw (DC 8 + the lycanthrope’s proficiency bonus + the lycanthrope’s Constitution modifier) or be cursed.

In full beast state, you resemble the beast of your affliction.  You are larger than the average beast, but smaller than a Dire version of the beast.  Your Strength temporarily increases by 2, your speed increases to 40ft, your hit point maximum is increased by 11 (2d10) temporarily, and you gain an additional attack action.  You cannot use armor or melee weapons.  Your AC increases by 1, claw attacks provide a 2d4+2, and bite attacks provide 1d8+2 damage.  A non-lycanthrope humanoid hit by a bite attack from a creature that carries the curse of lycanthropy must succeed on a constitution saving throw (DC 8 + the lycanthrope’s proficiency bonus + the lycanthrope’s Constitution modifier) or be cursed.

This is a three-part package.  You must add the feat and magic item to your character to activate all features. 

The feat will add the following: 1. An attunement slot to be used for the magic item (see below).  2. Resistance - Bludgeoning, Piercing, and Slashing from Nonmagical Attacks (substitute Nonmagical - Non-silver).  3. Increases your human form unarmed damage to 1d4+1.  4. Adds advantage to Perception and Intimidation.  5. Adds two actions, a claw and a bite attack to be used only with hybrid or full beast form.  6. Adds transformation slots/level in the bonus action area of actions.

The magic item will add the following which activates at attunement: 1. A +1 bonus to armor class.  2. A +2 to strength. 3. 1 extra attack. 4. Changes walking speed to 40 feet.

Skill Proficiencies: Nature, Survival

Tool Proficiencies: You gain proficiency with alchemist’s supplies. This is primarily used to make your sedation potions, but you have normal proficiency on it.

Languages: Two of your choice

Equipment: A amulet (A silver amulet to help suppress the beast within), 10 Potion of healing (vials of a potion used to sedate your frenzied state), and Spikes, iron (10) (silver-tipped).

Suggested Characteristics

You are naturally weary of others.

You wish to prevent the spread of your curse.

You can only dine on meat or other animal-based proteins, anything else will cause you to vomit.

You feel a kinship to wolves, and you often pack-bond with friends.

d4	Personality Trait
1	Your parents have been hunted and killed, and you want vengeance
2	You enjoy hunting in the wild and have a hobby for it.
3	A blue/blood moon occurred in your childhood, and you lost control.
4	I secretly transform far from civilization to release stress

d6	Ideal
1	I strive to prevent my curse from ever afflicting another (Good)
2	I live my life free and proud; no one can judge me but me (Neutral)
3	Sometimes I must go beyond what is allowed to defeat all the evil that cursed me (Chaotic)
4	The world rejects me so I reject it back, I cannot be one of them I will destroy them all (Evil)
5	I will submit to the will of the people, even if that will call for my head (Lawful)
6	I think both my people and everyone else deserve a chance, but they will bring my fury if they squander it. (Any)

d4	Bond
1	Family- Blood is all that matters.
2	The Pack/Society- What is best for the majority is what is right.
3	Friends- Those who stay loyal to me deserve the same back.
4	My lover- He/she accepts me and is all that I need.

d6	Flaw
1	I am slave to my base instincts.
2	The animal within me speaks, and sometimes I listen.
3	I committed an atrocity while in hybrid form and said I had no control; I lied.
4	I've grown to like the taste of humanoid flesh.
5	I kill other lycanthropes to assert myself as the alpha.
6	My confidence is a facade; it can be easy to make me believe I am a monster.