As an assassin...

In 13th Age, there is a background system for skill checks - essentially you allocate skill points an abstract background. then, when a skill check comes along, you roll against the difficulty, adding the background that is relevant. You explain why this is relevant in the game. I think it makes a nice background.

So, for Fate of the Norns, I propose the following:
  1. Ignore the skill boards and all the skills in the book
  2. Pick a number of backgrounds
  3. Assign your Essence in points/runes to them
  4. You can assign no more than four or your Destiny in (whichever is less) runes to any one. You can add 1 to this limit for every Disir level you have.
  5. Additionally, you gain one for your sub-archetype (assassin for Sceadegengan, enchanter for galdr, etc) because of your void rune. This is explicitly defined by your sub-archtype.
So, Björn the Berserker (Essence 6, Destiny 3, Level 12) might have
  • Rower on the Jarl's longship - 3
  • Apprentice to the great smith Wayland - 2
  • Lived in the wilderness for a month - 1
Marvin the Multifaceted might have
  • Lived in the wilderness for a month - 1
  • Lover of the ladies - 1
  • Merchant for a summer - 1
  • Saw a sword get made one time - 1
  • Got some basic rune lessons - 1
  • Sami-friend - 1
Norn Note: this might require tweaking. Animal Shapeshift, or various passives based on skills, might put a kink in this. Many of these cases can be dealt with by creating a background that actually gives the skill in question. For example, if you have a passive that relies on War Tactics, creating a background that is something like "Sub-jarl under Jarl Borg" will fill the need there.