Adept of the Seventh House, necomancer to cavalier Ambrose Epta. Penthos Adrastis gets his name from the ancient greek Penthos which is 'grief'. Adrastis comes from Adrastos the leader of the Seven against Thebes, who's name means 'should not run' or 'unescapable.'This, of course, makes Penthos 'Grief the unescapable', an accurate name for a living exquisite corpse.

One eye is slowly liquifying. Decomposing into wet putrefaction inside his skull, cultivating the decay. In constant agony, the only thing stopping it from rotting away his brain is necromancy, holding it in stasis, allowing it to exist in a frozen bubble of living death.
He periodically lets it advance, trying to tweak the decomposition just right so as to have a permenant battery of thalergy to draw from.

The preservation of the corpse and the stasis of soul, prolonging the space between life and death and between death and decay.

^ Ambrose Epta, gallant yet rakish Cavalier, a duelist, and enough a rake that people are like "you must be a shit cav" but he's actually decent. He makes an exception on his Behaviour for Pen.

Meaning & History
From the Late Latin name Ambrosius, which was derived from the Greek name Ἀμβρόσιος (Ambrosios) meaning "immortal". Saint Ambrose was a 4th-century theologian and bishop of Milan, who is considered a Doctor of the Church. Due to the saint, the name came into general use in Christian Europe, though it was never particularly common in England.

More information on the world and lore of the Locked Tomb series can be found here



The pair of them are horridly codependent, and though Epta is seen often enough having daliances, to seperate the two would be akin to amputating a limb. Remove ambrose from him and you may as well take his leg, his good eye, his left lung.
Viciously jealous, Penthos sabotages every relationship of Amborse'. Driving away every bed parter that lasts more than two encounters. Pen is 'hopelessly' longing and pining for his Cav, thinking he only ever spends any time with him out of duty. Desperate for Ambrose to love him back. He makes his condition worse to get Ambry to pay more attention to him, spend more time with him.

Pen does play up the 'innocent, fragile, feeble' image, infantilizing himself to some extant because he wants people (specifically Ambrose) to pay attention to him, to care for him.
And then he gets confused by why almost no one approaches him with adult intentions, apart from creeps.

"Seven for beauty that blossoms and dies"
The Seventh House, The Joy of the Emperor, The Rose Unblown is the seventh planet to be reborn in the Nine Houses System. Victim to a hereditary blood-born cancer, The Seventh has developed an obsession with the beauty of death. The house hopes to "perfect" their illness and harness the thanergy present within their own bodies to become more powerful.
The Seventh House embody the particular beauty only found in dying things. They are the rose hanging lush with decay, the vines that pull down walls of stone, the bloom of color in a terminal patient’s cheeks. They draw out moments of beauty, preserving people, places, and times in amber for later dissection and delectation.

As you can see to the left, when Penthos doesn't have on his eye patch in public, he wears a veil, so as not to disturb those with weaker consitutions.

Of course, on the Seventh, it's not seen as grotesque. Not to other adepts, at least. No, it's seen as a beautiful bit of necromantic experimentation, of necromantic art.

Just as the slow decay and degredation of the body from illness is seen as beautiful, so too is Penthos' decomposing eyeball, a teeny, but infinate supply of thanargy.

Writing of them can be found here.

In the event of the pair achieving lyctorhood, Penthos is under the impression that it will be, as The Unwanted Guest purports, "like swallowing a diamond." He thinks that he will simply swallow Ambrose's soul whole, that he would be carrying him around inside his heart. Keeping him close, keeping them together. Instead, he finds, immediately after ascending, that he was entirely wrong. He did not swallow Ambrose whole, but chewed and digested him down to the molecule. When he tries to pry Ambrose back out of him, all he can do is pry himself apart on a cellular level. Blasting apart into so much bloody pulp.
And thus ends a lyctor.
At least until God puts him back together. When he comes to, it is sobbing, wailing, screaming to give him back! Give Ambrose back.
But he can't. You cannot undigest a soul. Cannot undo metabolisis.
No matter how hard he tries to vomit out Ambrose's soul it won't come. He tries to pick out his marrow. His organs. His cavalier but there is no cavalier anymore.

There is only him. Penthose Ambrose.

Grief Immortal.

It should, then, be no surprise that Penthos Ambrose the First, Saint of Love, tenth lyctor to serve the Emperor Undying, defects to Blood of Eden the first chance he gets.
They want a pet lyctor, and while the assertation is made multiple times over the course of Nona the Ninth that you cannot leash a lyctor any more than you can leash a thermonuclear bomb, when that bomb slips the collar on himself and hand you both leash and detonation codes....

He does so because he feels like a monster. No, he knows he's a monster. He took something lovely and loved and beautiful and he ate him till there was nothing left. Of course he deserves this. He is the type of guilt-striken to climb into one of the burning cages himself, just to let the flames lick over him in penance. It doesn't kill him, it can't, but he doesn't care. He just wants it to hurt.

Where Cytherea the first said she was "the vengeance of the ten billion," Penthos the first is the grief of the ten. The grief of each lyctor, undying, imortal, unescapable. The Saint of Love is each and every saint's neverending grief, haunting them, god, and the universe.
Because of what he lost.
Because you cannot undo loved.

Excerpt from a full rewrite of Gideon the Ninth in Penrose's perspective:

“Come here, Ambry. Please. You know what we’ve come here for. You know what I must do. What you must do.” Penthos is proud to say that his voice only shakes slightly. That it might be written off as a product of the trembling in his legs.

Ambrose nods, sure in it, even as his heart races. Penthos can hear it. Could always hear it, the way he hears his own blood rush in his ears.

“We came here for you to ascend. For you to reach sainthood. To become a Lyctor. It would be folly to give that up now,” he says, not wavering.

Pen wants to cry, a bit. They had seen the Third, in the aftermath of her ascension. Seen the way the princess twitched and shook. Seen the way Tern had lain there, empty. Soon that will be them.

“Are you sure?” he asks, terrified, even as he already knows the answer. “I would not begrudge you laying down your sword.”

“No. Never. I am yours. I have been yours since even before we swore that oath. Even before I signed that compact.” Ambrose declares. His eyes are looking deep into Penthos’s, searching. “I only ask you take care of yourself, now that I won’t be here to do it for you.”

That’s what makes Penthos truly break, tears running down his cheeks, fat proper ones. He pulls Ambrose into his arms, chest to chest, an arm around his waist. Ambry cups his face, pressing their foreheads together.

“It has been an honor to serve as your cavalier all these years. An honor to be your servant and sick maid and caretaker. An honor to be your lover.” He kisses the necromancer, short and soft. “It will be an honor to serve you in this as well.”

Pen sniffs, his free hand sliding down Ambrose’s sword arm, gently pulling his rapier free. It’s heavier than he had expected, somehow. As if this weight would be easy to carry. As if Ambrose’s weight would be easy to carry.

“As I swore to you all those years ago.” Amb sniffs back his own tears, smiling wanly. “Come on Pen, say it with me. It’s not the same if you don’t say it too.”

It’s not fair, he thinks, hiccupping a sob. Ambrose is right, though. “Us. One flesh, one end.”

“One flesh, one end.” It’s the last thing Ambrose says. Leaning forward, to kiss him properly. Both hands cupping Penthos’s face, now that he can put down his blade. Free to hold his adept as he always wanted to be held.

Both their eyes slip shut, deepening the kiss.

When the blade pierces flesh, Penthos does not stop. Gasps into his cavalier’s chest as his sword slides all the way through his own torso.

Step one: preserve the soul, with intellect and memory intact.He’d done the same that Ianthe Naberius had—pin the soul in place through the heart.

Step two: analyze it—understand its structure, its shape.Penthos has known the structure and shape of Ambrose’s soul since they were children.

Step three: remove and absorb it: take it into yourself without consuming it in the process. He draws his cavalier’s soul into himself through the kiss. Unsure if this is kindness, or another cruelty.

Step four: fix it in place so it can’t deteriorate.It has never been easier to preserve anything. The specialty of his House coming into use for perhaps the first time in this entire blasted puzzle.

Step five: incorporate it: make the soul part of yourself without being overwhelmed. Pen swallows down his lover’s essence, his spirit, and feels it become himself. A new form of communion.

Step six: consume the flesh.This much is already taken care of. Ambrose’s blood has been pushed into and through him. The sword had taken care of that. Heartblood to heartblood, mingling inside.

Step seven: reconstruction. This is the most difficult, getting his own failing body to see this as a viable battery. In the end, it’s his own eyeball that cinches it. A new battery, intangible this time, but still there.

The pair of them fall to the ground, Penthos gasping and sobbing now, as he feels Ambrose surge though him. As he pulls the rapier out of both their bodies, his heart already sealing shut.

This is how a saint is born.

It is not until he staggers to his feet, bursts of thanergy zipping through him, not until he must use Ambrose’s sword as a cane, barely keeping himself upright, not until he opens his eye and everything is a slight bit clearer, that he fully comprehends what he has done.

Penthos is alone. Terribly, impossibly, eternally alone.

He has not simply swallowed Ambrose. Cannot simply carry him around inside his heart, as he had intended. No, he has chewed and digested his beloved, his dear Rose down to molecules.

When, from out in the hall, he hears a horrible explosion, Penthos drifts out like a lost revenant himself. When he sees the Duchess of Rhodes, standing and shining, despite the blood, proclaiming herself someone else, he does not question it. Does not question any of it.

When he hears the words dripping from her lips, searing accusation, it does not feel like condemnation. It feels like ablution.

“My name is Cytherea the First,” she had said. “Lyctor of the Great Resurrection, the seventh saint to serve the King Undying. I am a necromancer and I am a cavalier. I am the vengeance of the ten billion. I have come back home to kill the Emperor and burn his Houses.”

Penthos Ambrose can only cry in relief, begging his newly related older sister kills them all for what they have done.