Hypnos

"Welcome to the House of Hades, where... wait I know you, I guess that means you died out there, huh? Well don't be sad, though, pretty much everybody dies sometime!"

- Hypnos

Hypnos is the embodiment of sleep. He is one of Nyx's many children, and the twin brother of Thanatos.

He watches over the procession of newly-arrived shades coming before Hades, checking their names off his list. He is often seen sleeping on the job.

He greets Zagreus most of the time when the prince is killed and returns to the House via the Pool of Styx, and often gives unhelpful advice and a quip about whichever enemy or natural force did Zagreus in.

Affinity
If given Nectar, Hypnos will give you the Chthonic Coin Purse.

Hypnos' affinity gauge is maxed out at 8 hearts, requiring the gifting of 6 Nectar and 2 Ambrosia total.

Favor
Completing Hypnos' favor involves witnessing a series of events between him and Thanatos. To start, Hypnos will tell Zagreus that Thanatos has said some things to him that make him feel as though he's displeased his brother, and Zagreus states he will talk to Thanatos on Hypnos' behalf.

After Zagreus confronts Thanatos about Hypnos, periodically between runs Zagreus will encounter the brothers engaged in conversation. Thanatos will repeatedly criticize Hypnos' work ethic until finally seeming to discover a way to help Hypnos focus. Thanatos then praises the quality of his brother's improved work and apologizes for treating him badly. Afterward Hypnos will thank Zagreus for speaking to Thanatos, completing his favor.

Unlocking Hypnos' final heart cannot be done until after the full ending of the game, that is, until after Persephone has returned to the underworld. In order to do this, you must first also have given Thanatos at least 5 nectars. Getting Hypnos an autograph from Asterius or seeing the scene in which Dusa compliments his work is not required to unlock his final favor.

Autograph from the Minotaur
After dying for the first time while facing Asterius—whether as a miniboss or in the arena of Elysium—Hypnos will start asking Zagreus to get him an autograph from the Minotaur. In order to actually get him this autograph, Zagreus must first die a total of six times in order to hear six unique greetings from Hypnos: three of these require dying to Asterius himself, two require dying to Theseus, and one requires dying in the final boss room of Elysium. The game tracks which of the two deals the final blow, but it doesn't matter if you have activated the Extreme Measures aspect of the Pact of Punishment. After getting all six lines of dialogue from Hypnos, encountering Asterius as a miniboss will finally allow Zagreus to get Hypnos his prized autograph.

Quotes
"For quotes and dialogue regarding, please refer to /Quotes."

Relationships
Nyx: Hypnos usually addresses Nyx as "Mom" and still struggles with calling her "Mother Nyx" while in the Great Hall, which may reinforce Nyx's belief that her son is too dependent upon her. His loneliness, in turn, is bolstered by her request that he refrain from engaging her in conversation. Hypnos has grown so used to his mother's lack of praise that he has ceased to expect it; when Nyx tells him for the first time that his "efforts are to be commended", he immediately assumes someone else is doing the commending. He goes so far as to guess Hades is that 'someone', never once guessing Nyx herself would be the one offering praise. Regardless, Hypnos has only ever exhibited love for his mother.

Thanatos: Hypnos is initially kept at arm's length by Thanatos—who, like their mother, primarily interacts with Hypnos to discuss Hypnos' work ethic and job security. Such interactions consist of Thanatos lecturing Hypnos; he spares little time to talk with his twin otherwise. Thanatos expresses little faith in Hypnos, thus when Hypnos submits a report of immaculate quality, he wrongly assumes someone must have been assisting his brother. In contrast to his relationship with Nyx, Hypnos openly frets that his brother may loathe him—however he still adores both Nyx and Thanatos. Hypnos yearns for his brother's attention and company and, at one point, suggests Thanatos kill all mortals in one swoop so that the two of them could then spend more time together. Hypnos' relationship with Thanatos improves once Hypnos heightens his productivity, and as Thanatos—after Zagreus chides him for how "mean" he has been to his brother as of late—begins making an effort to be kinder to his twin.

Megaera: Hypnos freely offers Megaera the same type of advice he offers Zagreus whenever Megaera or Zagreus emerge from the Pool of Styx. At some point Hypnos begins harboring a small crush on her, the flames of which are fanned as she begins dying more often at Zagreus' hands—thus emerging from the Pool of Styx more often; having always perceived Megaera to be invincible, and ever lonely, Hypnos initially lets himself believe Megaera has begun dying more often just to see him, as if they have some sort of personal connection. However, Hypnos' pedestaled image of Megaera eventually loses its luster when Megaera—despite all his advice—continues losing to Zagreus. Though Hypnos no longer thinks of Megaera as invincible, he is easily able to overcome the 'rejection' since he genuinely enjoys being able to speak with Megaera at all; unlike the shades, Megaera and Zagreus actually talk to him.

Zagreus: Hypnos is the first person to greet Zagreus whenever Zagreus emerges from the Pool of Styx. As the staff member responsible for recording details of deceased shades and their deaths, Hypnos knows exactly how Zagreus has died and will offer advice on how to avoid a specific death or handle a specific enemy in the future. Although Zagreus has not always been kind to him (Zagreus himself admitting to Thanatos that he has personally "been mean to Hypnos a lot"), Hypnos enjoys having the opportunity to talk to Zagreus whenever Zagreus dies; Hypnos comes to not only view Zagreus as a friend, but as a 'real friend' after Zagreus speaks to Thanatos on Hypnos' behalf. Eventually Hypnos will consider Zagreus to be his 'best friend', or the closest he has to one.

Additional notes
Hipnos