[....................................................................... that is cheating
I'm gonna do a couple that are old/existing headcanons though because I know I have a lot of new friends]
☾: Sleep Headcanon: Delta sleeps in pajama pants and sometimes a t-shirt depending on the weather and his mood.
☠: Drinking Headcanon: Delta really doesn't like drinking because he wants to be completely in control of his faculties.
♒: Phobia Headcanon: He really doesn't like the idea of losing control of himself or not having power over what he does.
⋆: Sex Headcanon: Delta isn't strongly sex-repulsed, but the whole thing makes him pretty uncomfortable. He much prefers a relationship in which the pants are kept on as often as possible.
☮: Random Headcanon: oldie but still one of my favorites, Delta nicknames his computers and tech. They're utilitarian names to help him keep everything organized, but kind of cute nonetheless.
☻: ‘Like’ headcanon: Coffee. A lot.
♤: ‘Dislike’ Headcanon: He's not overly fond of bright colors.
☯: Pet Peeve Headcanon: When people ignore or don't know basic established facts, like saying something happens for no reason when there is a really simple explanation for it.
☄: Weather Headcanon: Delta loves overcast weather. It's cool and calming for him.
☼: Cooking Headcanon: Delta could probably bake pretty well if he wanted to, but so far he hasn't had reason to want to.