Robin grew up in a middle class family of mages. Her siblings were all born sorcerers, however she was born a warlock. Because of this, she was looked down on for having "lesser" magic. She began to learn ways of leeching magic from those around her in an attempt to strengthen her own mana.

When talk of her eldest brother Hawk, the prodigy of the family, joining a “Holy Grail War” began spreading, she knew she had to take that opportunity to prove that she could be better than what they thought of her.

Pre-Character Arc. Robin joined the war knowing full well that she was probably going to go down fighting. Her pretense was that she wanted to prove herself to her father, but it was a suicidal act of revenge.

Post-Character Arc. Robin met someone part way through the war. They changed her, acting as the father figures that she should have had. This new input on her life and actions made her rethink her life and what she was going to do.

You gain a connection to a summoned servant and the Holy Grail, which bestows multiple benefits. Masters also gain a form of clairvoyance that allows them to detect other Masters, and a Servant’s parameters, Skills, and Noble Phantasms, by using (spell casting stat + perception prof). Additionally, you gain three command seals which can be used for the following.

• Give your servant an order they cannot refuse.
• Give your servant a critical success or critical failure.
• Instantly teleport your servant to your side.

Parasite Warlocks are usually looked down upon, as they cannot acquire a proper patron for themselves; so they look to those around them and secretly siphon mana from an unknowing powerful mage, one just strong enough to not notice them siphoning power from them to feed their own magic. This person is usually someone near to you, whether it be a family member or your superior. Because of this, their magic often imitates that of the mage they are leaching from. These Warlocks must learn how to walk on eggshells around said “patron” so that they do not discover their magic is being stolen. However, there are rare cases where a mage may voluntarily offer their magic to the Parasitic Warlock.

As a Parasitic Warlock you can choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

Starting at 1st level, in order to aid deceiving your “patron”, you learn Encode Thoughts, which counts as a warlock cantrip for you.
Additionally, you have advantage on deception and persuasion checks as well as advantage against charm effects.

Starting at 6th level, you are able to consume mana from another being with magical energy. The target must make a constitution saving throw against your spell save DC. On a failed save the target takes necrotic damage equal to 2d6 plus your charisma modifier as you siphon off a portion of their life energy. With this newly acquired mana you can do one of the following:

• You regain hit points equal to the damage you dealt plus your warlock level.
• You regain a spell slot equal to or less than half your proficiency modifier rounded up.
• You gain one ability from the creature of the DM’s choosing that you are able to use for the next 10 minutes.

You can use this feature an amount equal to your charisma modifier. You regain expended uses when you finish a long rest.

Starting at 10th level, you gain the ability to redirect an enemy’s spell that was directed at you. As a reaction when a spell is cast directly at you, you can absorb the spell and instantly cast it back at the original caster. If the creature is casting a spell of 3rd level or lower, you automatically catch the spell and cast it back. If it is casting a spell of 4th level or higher, make an ability check using your spellcasting ability. The DC equals 10 + the spell’s level. On a success, the creature’s spell is caught and sent back at them.

Starting at 14th level, you can attempt to absorb the remains of a dying or recently deceased creature’s magical energy. When a hostile creature drops to 0 hp you must roll a charisma check against the target’s spell save DC. On a success you consume their entire essence, soul and body included, and your form morphs to fit that of the creature that you just absorbed as if having cast Polymorph. The creature must be of a CR level equal to or less than your level. This effect lasts for 5 minutes before you return to normal.