Desmond walked into the Corprusarium, with his little friend, Raven following. As the door creaked open, he seen something, horrible. Tel Fyr Corprusarium had become a vampire nest... Desmond looked at Raven and nervously said, "V-v-vampires, I didn't sign up for this!"
Raven slapped Desmond and asked rhetorically, "Are you a dunmer or a mudcrab?"
He replied, "A dunmer..."
She told him as he opened the second door, "Then let us enter, the bowels of the demonic vampire nest."
Desmond nodded and saw a vampire say rudely, "Oh fresh meat. Perhaps Lady Quarra will reward me!"
Raven muttered under her breath and suddenly a ball of red-hot flame emitted from her fingertips! She barked, "Wrong..."
Desmond charged trying to impale the demonic vampire only to miss and fall. He dropped his sword, and in the blackness of the cavern-like corprusarium, he heard a voice whisper, "You shall suffer, Dunmer."
Desmond grabbed for the ground as he was dragged into the blackness, he screamed, "Hel---". His screams fell silent as he was dragged into the blackness.
Raven screamed, "Die!"
She muttered under her breath, and a bolt of white-hot flame turned the vampire to ash. She sat down and thought, "They took Desmond, my brother... For that I will butcher them all!"
OOC: Sorry for short post.
Seeing as you apologized for the post being short, I cannot actually say anything against it. However I do recommend you try your very best to drag it out: describing the scene, the feelings of the characters and dialogue between them will do that well.
My problem with the opening paragraph is that you used too many commas; at least in my opinion. I haven't had the time to read this all through but would I be correct to assume Desmond's 'little friend' is Raven? If so, then you didn't need the comma before 'with his little 'friend'. Instead I believe the sentence should have been: Desmond walked into the Corprusarium with his little friend, Raven, following. (With that said, I'm not a master when it comes down to grammar and punctuation, so the commas before and after 'Raven' may not be needed; sorry if they're not.)
If there is another person (the 'little friend') then I think it should have been worded like this: Desmond walked into the Corprusarium with his little friend; Raven followed. Again, this may not be exactly true but it seems to flow better, in my opinion.
Another comma mistake I found was this: "As the door creaked open, he seen something, horrible." Firstly: your pet peeve of saying seen instead of saw hit you. Be sure to correct that. Also, there is no need for the comma before the word 'horrible'. If you added it there for dramatic effect then you should of used an ellipse (...); otherwise it looks silly.
I liked the bit where Desmond got nervous about the vampires but you should of just kept the 'v-v-vampire' thing instead of writing, "Desmond looked at Raven and nervously said... etc etc" you should have just wrote: Desmond gulped as the sweat dripped off him, "v-v-vampires... etc etc." That way you're showing instead of just telling he's scared. See the difference?
I still feel that the dialogue is too unrealistic and robotic. Same with the flow of what you have written. I hate to say it, but it's just so boring reading: 'Desmond looked at Raven and said...'. Throughout the whole chapter you're just telling us what's going on without us using our imagination. Plus, the dialogue is always predictable and stale; it feels as if the characters have no personality what so ever and with boring characters comes a boring story. To improve it you should give both characters little quirks- Desmond may always make a little joke, for example.
One small thing that bothered me was this: 'Raven muttered under her breath and suddenly a ball of red-hot flame emitted from her fingertips!' I would really advise against using exclamation marks when describing out of dialogue- it looks like something an excited child would do, to be honest. I also think that was a good chance to describe the magic and the death but you rushed it a little; at least in my opinion.
The same problem goes with the fight dialogue. All of a sudden the characters go from boring people to barbaric apes. Maybe the vampires would get away with saying such lame battle cries because they're the villains but the heroes just going 'die!' is really lacklustre; same with, 'they took me brother, now they're all going to die'. Even if Raven is a tough girl she wouldn't just sit there like that; emotions would be spinning around her head and if she really is a normal person then she'd just be crying and upset. If one of your relatives got taken away by vampires (most likely to be fed on) how would you feel? Angry? Yes. But you'd be traumatized, too. I really think that was a great opportunity for us to get an inside looking on Raven's emotions but you didn't let that happen.
Overall that chapter wasn't great but you're still getting better. Just try to give the characters a personality and describe the scene more! Keep it up, I look forward to the next chapter.