These headcanons are mostly serious ones. My silly ones will be a separate textpost!!!

Yoko Tanaka & Vampires

Definitely would have pointed, almost elf-like ears

The movie Sinners (an aside, awesome movie) definitely got vampire eyes the best, would definitely give her those

Super speed

Super strength

I think she'd be able to fade into the shadows, so to speak, like essentially hide herself in plain sight as long as there were shadows there

Supernatural hearing

Blood detection

Night vision

Canonically allergic to garlic

Need to be invited into private dwellings, like rooms

Fangs get bigger when in the presence of blood

Nails can get pretty claw-like

Cold, take on the temperature of their surroundings

Will bleed when cut but it is slow and viscous

Need to consume a specific amount of blood a day to sustain themselves rather than having to eat every [x] amount of hours, most just like to eat at standard mealtimes for the normalcy

Can sleep, don't need to, but a lot of them like to (esp. Yoko, she is basically a giant black cat)

Divina Gemson, Bianca Barclay, Kent Gemson & Sirens

Sharp teeth, almost like sharks

Scales!!! Their placement varies, but they can be just about anywhere!!! They are not continous, but they do appear places like the back of the hand or on the neck!!!

All sirens have good singing voices

Most of them possess a level-headed demeanor, this doesn't mean they can't be nervous, but they typically remain more composed than other students

They transform into different types of fish!!! All three of them are freshwater varieties, but there are also saltwater varieties.

When transformed, they get gills, a tail, fins, etc.

Fey-like in nature when transformed (mischievous in nature)

Need to be in contact with water or well-hydrated for their powers to work well

The lockets also prevent them from looking more siren-like, taking away most of their features aside from the eyes

without the lockets but still untransformed, I think they'd have the scales, fish-like ears (think Lagoona Blue), webbed hands and feet, fins on the forearms and calves, etc.

Siren song magic has different colors!!! Bianca's is a deep purple, Divina's is a light blue, Kent's is a deep blue

Enid Sinclair & Werewolves

Well, Wednesday S2 just confirmed A/B/O verse is real so... alpha Enid...

After wolfing out she has a sudden growth spurt, going through what is basically delayed lupine puberty

Wolves are hairy, you can't change my mind. Shaving doesn't really work for them

Super strength

Increased sensitivity to smells and sounds

Night vision

Just like they have retractable claws in human form, I believe they have retractable fangs as well

Ears get pointy in human form after wolfing out

Enid has scars from the incident with the Hyde

All werewolves have to be in a specific werewolf gym class after transformation that is basically just running around for an hour to get out excess energy

Really stupidly loyal to their loved ones

Good-natured, but often moody

Dog-like behaviors, like tilting heads, sniffing things, etc.

Hungry like all the time

Eugene, Wednesday, Xavier & Psychics

Psychics still take damage like humans, as that is what they mostly are

Specialized classes for the psychics to help them with their powers

I feel like psychics likely have a bit of a loner mindset by nature, as they are technically not a creature like other students and are rather a human with unusual powers

I definitely believe the Seer type psychics (like Wednesday) would have special counseling sessions or something akin to that where they can talk about and decipher visions

Seers likely also have nightmares more frequently than other psychic classes

I think some psychic types might get lockets like the sirens did if they struggle with controlling their powers???

I also feel like some psychics would struggle with mental health issues, migraines, or otherwise due to the brain-intensive nature of their powers

Ajax Petropolus & Gorgons

Okay, I'm going to be honest, I have changed the Gorgons a lot

The beanies are not for preventing petrifictaion, they are for the snakes since they are cold-blooded

They cannot stone themselves or one another (which is why in mythology, Gorgons live together)

Pulling a Monster High, they can wear sunglasses or colored lenses and it'll prevent stoning other people since you are not viewing their eyes in an unobstructed way

More snake like features, eyes with slits

Infrared vision (like some snakes)

Extremely good sense of smell

They hiss and have the snake tongues

Fangs!!!

Scaled in some parts of their body

They like to lay on the stones outside when it's sunny and warm

Need extra calcium in their diets, much like reptiles