The Many

Rather than drawing power from a connection with a singular entity, your pact is with a patron manifesting as a plurality of consciousnesses.  They may be a massive, localized swarm who have evolved into a united existence, or a far-reaching hivemind whose powers and members span the many planes. They may be an aberration from the Far Realms, divine or demonic in origin, or something else entirely. Your patron has instilled in you the knowledge that links the consciousness of a swarm, like a colony of ants -- and you are able to harness this power to gather and command swarms yourself.
Such patrons tend towards lawfulness, though your will as an instrument of their power may differ.

Expanded Spell List

The Many allow you to summon forth swarms to aid you. You may 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, and manifest as a seething mass of creatures.

Fiend Expanded Spells

Spell Level	Spells
1st	feather fall, shield
2nd	blindness/deafness, animal messenger
3rd	phantom steed, bestow curse
4th	divination, locate creature
5th	insect plague, arcane hand

Feast

Starting at 1st level, when you reduce a hostile organic creature to 0 hit points, you regain hit points equal to your Charisma modifier + your warlock level (minimum of 1). An organic creature is generally defined as any creatures that are not Constructs or Elementals, although final discretion as to which creatures are edible is left to the DM.

When you feast upon a creature in this way, you may command your swarm to devour the corpse entirely, leaving no trace of their remains. 

Sword of the Swarm

Starting at 6th level, your spell shots can include a spectral embodiment of the creatures in your swarm. When you deal damage with a spell using an attack roll, you can add 1d4 magical piercing damage to one damage roll against one of its targets, as the manifested spectre attacks your target before dissipating. 

Shield of the Swarm

Starting at 6th level, during battle, your swarm has become strong enough to surround and protect you, making you more difficult to hit. Your AC equals 13 + your Dexterity modifier while you aren’t wearing armor. 

Salvation of the Swarm

Starting at 10th level, once per long rest, when you take damage, you can use your reaction to meld into your swarm, reducing the damage you take from the attack by half. You vanish into the multitude, and reappear in an unoccupied space that you can see within 30 feet of you. 

Once you use this feature, you can’t use it again until you finish a short or long rest.

Dissipation

Starting at 14th level, your shared consciousness with the swarm has deepened to the point that your corporeal body is no object. As an action, you are able to temporarily give up your physical form, melding fully into your swarm. 

You can maintain this transformation for up to 1 hour, before you risk fully losing your mental connection to your physical form and being lost in the swarm permanently. 

- You gain resistance to piercing, slashing, and bludgeoning damage, and have advantage on Dexterity saving throws.

- You have a flying, burrowing, or climbing speed equal to your walking speed. (Choose one, as you manifest as an aspect of the creatures making up your swarm. If you have a flying speed, you may hover.)

- You gain the ability to split the swarm and command the groups separately. Once per transformation, you can cast a modified Mirror Image as a reaction. Each of the three breakaway swarms manifests taking 1/12 of your current HP. Their remaining HP is restored if you reconvene with any surviving swarms when the spell ends.

Once you use this feature, you can’t use it again until you finish a long rest.