Today I woke up from not enough sleep into a post in /r/DestinyTheGame asking why the Vanguard is bald. I felt compelled to write a silly answer, copied here and slightly reformatted:
Well, as so many things do in Destiny, it begins with the Traveler. You see, Guardians weren't chosen at random, or for some abstract idea of worthiness—what would it matter, if their past lives were going to be erased?—but for having a little bit of unicorn DNA¹, retrocausally implanted² from the Traveler reaching back from the end of the universe while trying to defend itself from the Vex. Every time your Ghost resurrects you, it plucks a hair³ from your new form as the ongoing cost of that power over life and death. “Expensive” resurrections, such as from very long falls, being killed by other Guardians, or short-range explosions, can take several hairs at once, and even healing from critical injuries takes up fractions of a hair. This cost can only be circumvented if it is impossible, in any timeline, for it to have been carried out.
So as Guardians learned to be Guardians proper, as all the dust settled through a combination of science and revelation, only the completely hairless were considered to have been “broken in”, since before that happens, as was exploited many times in the era of the Warlords, it's possible to mortalize a Light-bearer simply by cutting off the rest of their hair. Naturally, most Guardians learn to wear wigs or other replacement head coverings⁴, often custom-made to match their original appearance. But the Vanguard alone are forbidden from it, as a way of symbolically taking on the burden of how best to handle this power. Sometimes others choose to copy their display: Shaxx, Banshee, and Rahool are all bald or close to it. Saladin Forge with his short hair is is demonstrating actively courting danger when he shows up with the Iron Banner. Poncho still has mixed feelings on the inside but puts her hood up to show solidarity with her pack. The planetary vendors are too far from the City for it to have the same meaning; Tyra's the same, with the addition that civil life on the Farm leans counterculture to the Vanguard anyway. The Drifter couldn't care less.
And there you go.
¹ Or an equivalent fragment of unikernel base code, in the case of Exos.
² Occasionally this surfaces consciously, especially under stress. Remember Cayde talking about his “beautiful, beautiful horn”? Would an entirely human-based Exo really be so attached to that as part of his body image?
³ Or error handling token, aka H_ERR
, in the case of Exos.
⁴ This was one of the main early opportunities the Everis family leveraged to become such an incredibly powerful force in the Tower economy today.