Animal Familiars are a new addition in Hades II. There are a total of 5 companions that can be recruited. Each familiar boosts the chance for a certain type of resource to appear, and will gather that resource for you (when directed, not automatically). Once recruited, the familiars can be upgraded to boost their abilities. One familiar can accompany you each night.

To unlock animal familiars, you need to complete the incantation Faith of Familiar Spirits. You will learn this incantation from Hecate when she makes a comment about bringing a familiar to assist you after defeating her a few times. The incantation requires 2 Nectar (obtained as a room reward, or from the Wretched Broker) and 1 Lotus (flora found in Oceanus), and will unlock familiars and give you 3 Witch's Delight, which you can now use to recruit familiars.

To upgrade your animal familiars, you need to learn and complete the incantation Bravery of Familiar Spirits. This incantation requires 1 Wool (reward for defeating Polyphemus) and 3 Wheat (grown from Wheat Seeds found in digging spots in the Fields of Mourning). Completing the incantation will give you 3 Witch's Delight, which you can now use to upgrade your familiars, or recruit any you haven't yet befriended.

You will need more than the 6 Witch's Delights given from those two incantations to recruit and upgrade all of the familiars. You can craft Beast-Loved Morsels on the alchemy tab at the cauldron for 3 Witch's Delights. The recipe requires 1 Nectar (obtained as a room reward, or from the Wretched Broker) and 1 Star Dust (reward for completing Chaos Trials). The recipe takes 14 Whiles to cook.

Frinos is the toad that hangs out in the respawn area outside Melinoë's tent. He is the easiest familiar to recruit as he hangs out in the Crossroads. You have likely already talked to Frinos when spawning in the tent, but if you haven't you may need to talk to him once before you will be able to gift him a Witch's Delight. While accompanying you, Frinos will hop about, absorbing foes' ranged shots that might have struck you instead. Frinos also gives you bonus max Life, and bonus chance of finding Lost Shades to collect Psyche. When directed, Frinos will compel the Lost Shades so that you can collect Psyche without needing to complete the mini-game.

Raki is a white raven, who can be found in Erebus. The first time you encounter him you can greet him, and he will leave. The second time, you can offer him a Witch's Delight to recruit him as a familiar. While accompanying you, Raki will occasionally peck foes for 5 damage, leaving them marked. He also gives you an innate critical chance, and bonus chance of finding outcroppings. When directed, Raki will mine from the outcroppings for you.

Toula can be found at the docks in the surface route, after defeating Polyphemus and before entering Thessaly. You can greet Toula the first time you meet her, and the second time you will be able to give her a Witch's Delight to recruit her as a companion. While accompanying you, Toula will enter each location with you, then curl up to nap near the entrance. Sprinting near her will activate her to attack nearby enemies. Once she gets bored she will lay down, and you'll need to sprint near her again to re-activate her. Toula also gives you a bonus Death Defiance, and increased chance of finding Fishing Points. When directed, Toula will catch the fish for you.

You will first meet Hecuba in the Crossroads at the beginning of the game, where she hangs out with Gale. After a few runs they both disappear from the Crossroads, having been sent on scouting missions. To recruit Hecuba, you will need to find her in Echo's room in the Fields of Mourning. Hecuba is Hecate's familiar, and you may need to interact with her in the Fields of Mourning a few times to get the dialogue from Hecate giving you permission to bond with her. While accompanying you, Hecuba occasionally stuns surrounding foes for 1 second, and digs up life or magick restoration in a pinch. Hecuba also gives you bonus max magick and bonus chance for digging spots. When directed, Hecuba will retrieve resources from a digging spot for you.

You will first meet Gale in the Crossroads at the beginning of the game, where she hangs out with Hecuba. After a few runs they both disappear from the Crossroads, having been sent on scouting missions. To recruit Gale, you need to find her in the last room of Olympus, before entering the boss fight. Like the other familiars you will need to greet her once, as well as get permission from Hecate to recruit her familiars if you have not already recruited Hecuba. While accompanying you Gale leaps in harm's way then deals 250 damage up to 3 times per region, 30 seconds apart. Gale also gives you bonus dodge chance and movement speed, as well as bonus chance of finding flora.

Fated Prophecies
Familiar Confidant - Confide in Frinos 6 times (also grants the Steam Achievement)
Close Companions - Bond with 3 familiars
Beyond Familiar - gain all familiar bonds with any familiar

Steam Achievements
Familiar Confidant - Confide in Frinos 6 times. You do not need to recruit him as a familiar to get this achievement.
Animal Whisperer - Recruit all 5 familiars
Beast Master - Fully upgrade all 5 familiars
Unfamiliar Forms - Alter the appearance of each familiar. For this you need to complete the incantation Alteration of Familiar Forms, which you will learn from Circe. The incantation requires 6 Wool (reward for defeating Polyphemus), 6 Fate Fabric (obtained from the Wretched Broker, or sometimes offered by Arachne), and 1 Flux (mined from outcroppings in Chaos). After completing it, you can unlock new appearances for your familiars that you have fully upgraded by interacting with them in the training grounds.