If you want to interact with these characters, please ask Marc permission and have him write for them:
Hatticus
Commander Mormont
Jarl Torbin (and yargle)
The Jarl's one living son
Asmund
Obitus
Nunwe and Nwoke
Silaluk
Stig
Ivar Ofri
Kettil Spak, the spymaster
Lady Ingrid Balkr, Master Architect
Lord Raul Frosli and Lady Runa Frosli
Lady Saga Sisr
Krisom
If you think of an NPC to add to this list, comment below.
Marc can grant special permission to allow you to write for these characters, but when using them, you must consult him first.