I enjoy thinking about the culture and etiquette around Ghosts and their Guardians- how they interact, how other guardians interact with other Guardians Ghosts, etc. Here are some of my favorite headcanons
-It is extremely rude to touch anothers Ghost without the Ghosts explicit permission. Some Guardians prefer no one touches their Ghost at all.
-Guardians can feel when another person (doesn't have to be a Lightbearer) touches their Ghost. We see some characters react to their Ghosts being touched but NOT when the characters eyes aren't on their Ghost. I like to imagine that the Guardian feels some sort of a phantom touch against their Light and/or own body.
-Being allowed to touch another Lightbearers Ghost is seen as an ultimate sign of trust.
-Ghosts that have shells with moveable fins will often waggle their fins against another Ghosts in a greeting/handshake.
-I swear I have read this one mentioned in lore but I may be misremembering, but Ghosts sleeping in piles. Those without their Guardians making giant mountains of Ghosts, and Fireteam Ghosts all huddling together while their Guardians sleep.
-I already posted this on it's own, but each Ghost has a song that connects them to their Guardian. Everyone has their own unique melody, and while the Ghost can recreate it, only they can hear it.
-If a Ghost dies before their Lightbearer, it's traditional for the shell not to be buried but instead carried around with the now lightless person if possible. (If the shell can be collected) Since they went on so many journeys together while alive :(
-Many will make the shells into arm bands or necklaces, something that they can always keep on them regardless of if they have their armor on or not.
-Can a Lightbearer die their final death and their Ghost live on? I guess this is more of a question than a headcanon. If they can, I like to think that the surviving Ghost is considered an outcast, no matter the circumstances of how it happened.
-This feels canon in my heart, but a Ghost will do anything and everything in their power to keep their Lightbearer from their final death including sacrificing others or themselves. We see multiple cases of this happening within the lore of Destiny 2, (Brya and Eris, Blue literally killing a person for Drifter after he was first Risen) but I feel like they do it because they truly do *Love* the person they rose. The other half of their soul. It could also be because they were created by the Travler to essentially make a Guardian- a protector of humanity. They can't protect anyone if they're dead.
-When Ghosts feel a strong emotion, their Lightbearers preferred method of Light can manifest on their shell. For example, a Ghost who has a Solar wielding Warlock feeling burning hot to the touch when angry- or a Ghost with a Stasis Hunter making little snowflakes when overjoyed.
-There are absolutely mean girl Ghosts who rag on Ghosts who haven't found their Lightbearers yet.
-I'm fairly certain Ghosts can get jobs, or at least it's been mentioned within the lore. Librarians, Secretaries, etc. (How do they get paid? What would they even buy with their Glimmer?) Anyways, certified therapist Ghosts who have special shells to signify what they are.
-We have not seen it yet, but I believe that Ghosts can revive any species they desire. They were originally created to protect Humanity which is why they mainly choose Exo, Human, and Awoken for their Lightbearers. We have seen them choose Hive, but I want to see Eliksni and Cabal Lightbearers.
I could go on, but I don't want to make people scroll past a wall of text on their feed! Feel free to ask or message me if you wanna yap about headcanons, I don't bite!