In the comments, feel free too share your own headcanons as well!!
• Grian actually wears hearing aids! (He lost most if not all of his hearing do too gun shots and the like during his time at YHS).
• I actually believe Grian and Wilbur are related somehow! (In my head canon, Wilbur while he was in a foster home summoned Grian via watcher ritual! When Grian showed up, the first thing he saw was a terrified little Wilbur that wasn't expecting the ritual to work. Grian, at the time, was in his watcher form which is down right terrifying too humans. Wilbur began to cry and Grian panicked, having not been around kids in a long time. Grian adjusted his form into what you see today, copying some of Wilbur's attributes. And from that, Grian took the place as Wilbur's older brother as Wilbur grew up. An accident happened that caused the two too be separated and the rest is history).
• I'm sorry, I got a bit off topic there!
• Grian actually weighs about 105 lbs. (This is because he is severely malnourished and is permanently stuck in the body of an abused 12 year old boy).
• Even though he can barely hear, his eyesight is phenomenal! (Grian can actually see in the dark and several feet away).
• Rarely sleeps at night because 1) he's immortal and doesn't need too and 2) night terrors so vivid that the seem real.
• Can fluently speak Japanese and has a tendency to mumble in Japanese when alone.
• Forces himself to over work so that, when he's accidentally startled, he won't react to violently.
• Can shoot a gun, wield a knife, and treat very severe wounds (y'all know why).
• Doesn't need to eat but enjoys the feeling.
•In actual years, Grain is over 1,000 years old but he doesn't like to count those years. So when asked, he just says he's in his 20s.
That's all for now! I might do so more in the near future!