I just don't see Giller as older than Darken let alone Jeziah. It's a false assumption that a grey hair or two makes someone older; Giller just looks more youthful overall. I really wish the show had given us more details about things like when Jeziah trained with Zedd, and how old Darken was specifically. But yes, Giller has definitely got a Severus vibe going! I'll write a specific Giller fic/some artwork to make it up to him. That uniform pic in the link gives me Thoughts :D