Hello! I love writing Gumayusi and I'm always more than happy to talk about tacenda (although are they headcanons if I'm the author...?). Anyway, where to start? In tacenda, I think his core characteristics are pretty much the same as the one in most other fics: intense loyalty, patience, mental strength and resilience, confident, and very rational.

His role in the team is pretty much the same—he's the rock and the foundation of the team. He holds them together, especially after things fall apart. In tacenda, particularly with Faker being somewhat...shall I say unpredictable? It's really up to Oner and Gumayusi to hold things together and if Oner falters, then its all Gumayusi.

Originally, I wasn't going to give him too hard of a time backstory-wise, but as the joke goes—happy people don't go out to fight dragons. For now though, all I'll say about his backstory was that besides "Folk Hero", the other background I would have given him was "Gladiator".

His least favorite spell, at least for now, is Arcane Eye, which is a spell that creates an invisible eye that can move around and look at things for up to an hour. He can't cast this and he doesn't personally know anyone close to him that can, he just doesn't like the spell. His favorite is any kind of healing spell/ability for probably obvious reasons.

If he ever meets Jeesun (or Bang, if Gumayusi somehow makes his way into the realm of the dead), he's immediately going to find himself adopted. Bengi has had to stop himself from telling Gumayusi that he reminded him of another range he used to know. One of the first things he asked Deft when he joined the Guild was to teach him how to pick locks and use Thieves Tools and thus Gumayusi is currently the only member of T1 who knows how to use them. This is also a skill he's told himself he's never going to forget.

Despite everyone else on T1 being non-humans, he's also the one who can see the best in the dark! There are mechanics behind this, but its still interesting. His Ranger class specification began because he liked to run off into the deep woods as a kid with a bow and just vibe until he had to come back (read: his eldest siblings dragged him back before he could accidentally come across some monster or trip into another neighboring plane like Innovation) but almost all of his other skills, including the fact that his favored enemies are Monstrosities instead of Beasts are from a single, but three year long unfortunate event.

He's also the one member of OGK that consistently remembers that Zeus doesn't actually need to breathe as a Air Genasi Lineage, despite Oner having known Zeus for much longer and Keria being a Lore Bard. He finds the fact that Oner can purr and that his eyes can dilate just like a cat's really cute, but that's not going to stop Gumayusi from relentlessly teasing him for it. From talking to Keria about various monsters and planes, he's fairly certain he knows Chovy's identity as a dhampir but he hasn't asked yet and Keria doesn't realize that Gumayusi's pretty much put it all together. He is, however, the only person Keria's told about Doran being a Reborn.

This is just some stuff I've gotten off the top of my head but this answer is getting a little long, sorry about that, so that's it for now! I love talking about Gumayusi and tacenda, so thank you for the ask <3