His pod is very cosy, which is to say it's claustrophobic and he can't move his arms and legs and he barely has enough room to try to push himself closer to the dome of tinted glasslike material separating him from the room his pod is in. But the room is circular, and not that badly illuminated, so he can make a lot of it out, though he might wish he didn't.

There are three other pods like his, arranged in a circle around the center of the room. A mind flayer is standing there, looking at an elevated pool of glowing yellowish liquid, its back to Astarion. It looks over its shoulder at him when he materialises inside the pod, its expression too inhuman to be readable despite the sudden animation of its face tentacles, then looks at the pool again to reach into it and grab... something... from it.

Oh he bets it's something disgusting.

That depends on how he feels about weird squirming tadpoles. The illithid floats over to Astarion's pod and the pod opens at a thought—

Which means Astarion can talk. "Excuse me! I believe there may have been a misunderstanding. I am not Cazador."

The illithid's words form in Astarion's mind:

Your identity is immaterial.

"—I'm sorry? No, you see, I was in Cazador's manor when you attacked but I am not Cazador, he is on a trip—"

We care not about the one of whom you speak.

...wait, so this wasn't targeted? It was just—random?

All will bow to the Absolute.

And without waiting for a response, the creature leans forward to bring the disgusting tadpole to Astarion's left eye. From this close he can see the circular rows of sharp teeth and the eyes to either side of its "head" and the four little tentacles—

Aaaaargh, there must be something he can do—

There isn't. The creature lands on Astarion's cheekbone and waddles the rest of the way up to his eye and its four little tentacles irresistibly push Astarion's eyelids open so that it can make its way around his eyeball and into his skull.

He doesn't pass out, though he wishes he would. Instead he feels the pressure of the larva making its way up his eye nerve all the way to his brain. And people don't have a sense of touch in their brains so even though he feels like he should be able to feel it there all it feels like is a dull pressure in his skull that slowly fades as the tadpole flattens itself against his brain.

His brain.

He has a mind flayer tadpole in his brain.

It's a good thing he's a vampire because he thinks if he had a normal digestive system he'd throw up and that would just be pointlessly making his day more upsetting. He'd been having such a nice bath.

The illithid leaves him to his suffering, letting the lid of the pod he's in fall shut again as it turns to leave. A sphincter-like door (that looks a bit like an enormous asshole) opens to let it through and then closes again, leaving Astarion alone with his thoughts.

Well, alone with his thoughts and the three other poor souls in the other pods.

Good. Great. Awesome. Terrific. Wonderful. Absolutely fantastic. He's ecstatic, really, that's exactly what he wanted in his life after two hundred years of slavery and torture by a sadistic vampire overlord, is be kidnapped by psychic octopus-people who are doing some kind of absurd mind surgery on him using disgusting squirming toothed worms. No, really, there's nothing in this world that he wanted more than this—

The ship suddenly shakes rather violently, the way ships tend to do when they are hit by something either very heavy or going very fast. Astarion's cosy pod at least means he doesn't get too badly jostled—there are not enough degrees of freedom for his limbs to get jostled—but it's still dizzying. And there are more such violent shakes, one after another, indicating that, well. Something is going on. The mind flayers are not just peacefully kidnapping harmless vampires from their masters' baths with zero resistance.

Good for whoever's doing the resisting. These mind flayers need some resisting. He hopes they're being resisted very violently and bloodily, that'd be the best kind of resistance.

But then there's a lurching feeling along none of the normal spatial dimensions he's used to and it's even more dizzying in a completely different way, like having your stomach be pulled out of your body without going through any other parts of it.

why is this happening to him

The assault on the nautiloid continues, and the decrease in flight stability suggests that whoever's attacking is very plausibly winning the fight. There is occasionally a noticeable feeling of decreased weight that suggests the ship is losing altitude but it's unclear if the losses are due to damage or tactical flying.

And then there is fire.

In his long, long life, Astarion tried praying to all manners of gods. Good gods, neutral gods, evil gods, lawful gods, chaotic gods. None of them ever answered.

There is only one god he could forgive this from.

So when he thinks he might be having his last thoughts in the face of the conflagration, his prayers go to Tymora.

But he doesn't die. The fire mercifully does not destroy his pod, and him with it, flammable though he may be. But it does destroy enough of one of his neighbours' pod that she manages to kick herself free and jump out of it.

...the pointy ears and froggy skin, she's githyanki, which means—

"Hey! Excuse me! I need help!"

She does not look at him, either unable to listen or entirely ignoring him. After getting her bearings she steps through the ex-asshole that is now just a round charred hole on the wall and then she's gone.

Fuck. Come on!

Wait, maybe the fire could've weakened his pod? That'd be really useful, and some further pulling on the disgustingly fleshy machinery holding him suggests more give than there was before.

Ah, the beauty of being in a ship that is also a living thing. Means that if you damage it you are hurting it and so everything starts working less well.

Mind flayers are stupid as fuck.

He can make some progress towards freeing himself, but the thing that finally allows him to shake himself loose is another bizarre cross-dimensional lurching feeling.