*contains spoilers*

So now we're on episode 3, I think it's perfect opportunity to discuss how evil the vet is....

Theories:

- He's a murderer. Most serial killers start with harming animals. And we know for a fact, animals take an instinctive dislike to him, though he saved the dog for some reason and killed the cat.

- He might have something to do with Hyun Ji...?

- He transfered to the college for nefarious purposes. Maybe he wants to get close to someone or something?

I think it's logical to guess that he's either directly or indirectly tied to/responsible for hyun ji's death/predicament (I'm not 100% convinced she's dead yet), but I'm not certain of much. he's a mysterious guy, tho, & I was holding out from judging him---until this episode. he thoroughly gave me the Creep Vibe in this one. that cat totally did not want to be touched, but it's the second time we've seen an animal respond negatively toward his touch. now the cat is dead? I've been thinking along the lines of the supernatural world & how joo hye sung might be connected... I first thought that whatever happened to the cat could be a result from coming into contact with his blood, but I also wonder if just killed it with his bare hands. idk what to think tbh.
In popular ghost folklore, animals go haywire when someone from the ESP spectrum comes near them
They bark, their hackles rise, show their teeth...
Which indicates there might be a bit of supernatural within Hye Sung!

All ghosts, have a "glow" about them except for Hyun Ji, indicating she might be comatose somewhere
hahaha....how can you miss the evils he gives every animal right after they bite and scratch him and the "sinister music" that comes on, when he was taking of shirt, revealing an occult(?)  symbol burnt on his back (well it looked like it was burnt)

I actually thought he was going to be the second male romantic interest LOL, but I'm happy he isn't.
it wouldn't be the first time I undervalued the menacing hints of a bad guy ¯\_(ツ)_/¯ but is THAT what it is on his back? do I ever feel blind, because it looked like a curiously nasty scar to me. I checked the db recap; lollypip calls it a creepy black tat similar to the mist that pushed bong pal's mom. I need to go rewatch that scene.

re: hyun ji: yes! hopeful wishing aside, I've felt like she's a comatose patient since ep 1. it could go either way but it makes just as much sense, if not more imo.
I agree with all of the theories so far but i also think that he is already dead and the body got possessed through the scar on his back somehow.
Other reasons why i think he is dead because when he got UNEXPECTEDLY scratched by the cat he gave off a bad vibe as if an evil ghost is inside of him & didn't like getting hurt or some evil ' something ' didn't want to be leaked out, or whatever, since it would show his true colours.
But when he got bite by the dog, when there were many people around, he was EXPECTING it, so he knew he had to control himself & make himself seem like a nice person by also saying that he will take care of it & that could also be a reason why he didn't kill the dog but killed the cat.
This is just a small part of my theory anyways haha
just by how this story could play out, & considering all the characters & the roles they fill & how they might all connect & yadda yadda, I've suspected hye sung is somehow linked to hyun ji's situation. lollypip said the scar reminded her of the mist that killed bong pal's mom---I'm not so sure about that. I did go back & check, & while it looks like it might be tattoo from from away (as per lollypip's description), it is definitely a scar. idk that I would connect it to the black mist by appearance alone, but I won't be surprised if hye sung is possessed or related by association to that dark entity (who I also suspect is responsible for hyun ji's intended death & coma... or death, if you don't think she's comatose).
After watching episode 4 I'm 89 % the vet is the spirit that killed Bong Pal mom's and the spirit his dad his chasing around.  I also believe that he is the reason for Hyun Ji predicament ( whatever it is, not convinced she is a goner yet.) He totally came on campus because he is trying to find Bong Pal dad. But I'm 99 % sure the Vet is not totally evil but possessed by an evil doing up to no good.
OMG.

Did anyone notice how Hye Sung sidestepped our favourite ghost....?

This man has self-control. To see ghosts but not react to them
I am thinking that his real personality was revealed really early on in the drama. I am also on the theory that he was possessed by a spirit (same with how it was in OH my Ghost). I am really enjoying the drama!
lol Bong pal is totally in denial that his ship has sailed toward our favorite ghost. Anyway Vet-nim is evil, I'm not a cat person but wow I felt bad for that cat.
the cat's death sounded excruciating. I mean, I expected him to just go & snap its neck but, damn, that was a lot cracking...

& yeah, hye sung can totally see ghosts. it's something I've been wondering about & him side-stepping her is enough confirmation for me. unless this drama wants to throw a plot twist our way, I am also pretty certain that hye sung is possessed (specifically by that malicious people-pushing spirit) & was the one looking for bong pal's dad. since hye sung didn't or can't find him, I believe that's why he moved business locations & took up a job at the university---bong pal is a student there. altho why he isn't more proactive in approaching bong pal, unless he's observing &/or he wants to be cautious due to hyun ji's presence, idk. all he's done so far is take over teaching some econ-related course of bong pal's (which, two things: 1)I bet the original teacher didn't voluntarily leave, if you catch my drift, & 2)as if a vet prof overseeing a course for econ majors makes any sense, but I digress).
The cat!
What about the girl? :D
@theartwit

Yes, and going by your original theory, you think he has something to do with the position Hyun Ji is in now, so to see a girl he possibly bumped off, or tried to bump off, must've caused the almightiest of shocks, but he didn't react, like...at all? Except in a passive aggressive way, when Bong Pal is arguing with Hyun Ji and he asked if there was a problem. I don't get it either. Bong Pal is his stake, but he's doing nothing to approach the guy, except possibly get his crush to hang onto his every word.

Yeah! A vet teaching an econ class! What on earth? :D I bet you're right about him disposing of the previous professor

*spoiler*
In the preview for ep 5 (it's one more week, I know ~groans~) he's looking at a picture of Bong Pal's family.
He's after them, big time
I'm just surprised he's not crossing of their faces as he goes
if I see someone who isn't glenn rhee die in a show then I'm like, "nbd," but if I see something like a dog get a scratch on his nose then prepare to hear me scream. TBH.

in all seriousness I felt bad to see her go like that; I hope it was less painful than the cat's demise.

re: hye sung: maybe he's had long years of composure practice! I get the feeling that this entity's been at this game for quite some time, altho I'm most curious to find out what he/it gets out of killing people in the first place. is this a corrupt being that perpetuates evil acts for some kind of gain? or does it even have a reason? it shoving bong pal's mom also seemed to affect her spirit, because I can't think of a good cause as to why she would re-appear to her son at the funeral all malevolent-like.
I seriously still didn't understand why he killed the cat?