Eddie loves nicknames/pet names so he calls Jonathan = Jonny/"Bambi" & Steve = Stevie/"Sweetheart"
Steve & Jonathan don't normally use pet names for each other, it's not really their vibe but do on occasion use "babe". (This is also what Steve calls Eddie.)
Jonathan called Eddie "love" on accident one time and Eddie's reaction was so cute that it's now basically the only thing he calls him.
Although the three can't married, Steve & Eddie eventually change their last names to Byers. This was decided because purely by a game of rock, paper, scissors. (They're all secretly happy that "Jonathan Munson" didn't happen.) | (This was a joke in my fic "Have to Have You" but I really like it.)
Eddie & Steve: Very pro-PDA
Jonathan: Easily flustered by the PDA but likes it
Spicy Steddithan Headcanons
Steve & Eddie: Switch/Verse | Jonathan: Bottom
Eddie & Jonathan hooked up before ever going on a date.
Steve & Eddie hooked up on their first date.
Steve & Jonathan hooked up exactly a week after their second date.
Jonathan's sex drive isn't as high as Steve & Eddie's but is very happy to watch.
Steve (obviously) likes to be manhandled, roughhousing with Eddie & Jonathan almost always ends up in sex.
Steve: 100% has a praise kink, Eddie & Jonathan actively use this knowledge against him. (A little "good boy" here, "You're doing so good" there, always during moments where Steve can't just kiss them to shut them up.)
Jonathan: Has both a praise kink and a mild degradation kink. Steve takes care of the praise while Eddie takes care of the degradation. (It felt too real coming from Steve, neither enjoy it.)
Eddie: Biting kink, he's a fukin vampire. Steve & Jonathan are happy to participate but have had to convince him to leave marks in places that can be covered.
Being a photographer, Jonathan is always behind the camera so there aren't a lot of pictures of him... Except for in Steddie's private collection which contains multiple photos of Jonathan on his knees.
Eddie: Very loud during sex, ends up with his mouth covered a lot if it's outside the bedroom.
Steve: Quiet but specifically in the "whispers and moans directly into your ear" kind of way.
Jonathan: Does his best to stay at an "appropriate" volume, results in whimpering.
If there aren't a pair of lips on his/something keeping his mouth busy, Eddie can and will have a whole conversation during sex.
Eddie & Jonathan will have sex in the back of Steve's car, Steve is very thankful he's not an easily distracted driver.
They were best friends in elementary school after meeting at the park
Slowly stopped hanging out in high school due to rumors about their "relationship"
Even though they stopped hanging out, Eddie still gave Jonathan 🍃 for free but refused to provide anything else
Aside from Nancy, the only person Jonathan said goodbye to before moving to California was Eddie
Was unaware of it at the time but the reason he was encouraging Steve to get Nancy back was due to his own jealousy about her relationship with Jonathan
Jonathan & Eddie start dating a few months after Vecna is defeated but only the group knows (the party + older teens)
On a random day, Jonathan called Eddie "love" instead of by his name
Eddie's brain ERROR 404-ed for a good minute before just kissing Jonathan
Mostly when alone, Eddie calls Jonathan "Bambi" because he "looks like a deer" (And looked like a deer in headlights when Eddie kissed him in front of everyone for the first time)
Following on your post about the Byers speaking Spanish, what is Hopper's reaction to this? I bet they forget he can't understand them. Loved the hc, as a Spanish speaker I approve
Hopper gets irritated when the boys are VERY OBVIOUSLY talking about him but for his own sanity he chooses to believe they're saying good things
He definitely carries around a Spanish to English dictionary
+ Bonus: Jane ends up catching onto the Spanish a lot faster which only causes Hopper to be even more confused at the dinner table
No one is dead in my headcanon universe okay, they're all happy 😭