User blog comment:Jabberwokk/Primarch's Roles/@comment-3514402-20120907063615

A conversation between Kasper Hawser and Heoroth Longfang from Prospero Burns best sums this up.

"When the Allfather sired His pups," said the priest, "He gave each one of them a different wyrd. Each one has a different life to make. One to be heir to his throne. One to fortify the defenses of the Imperium. One to guard the hearth. One to watch the distant perimeter. One to command the armies. One to control intelligences. You see, skjald? You see how simple it is?"

"So what is the Wolf King's wyrd, Heoroth Longfang?" Hawser asked. "What life did the Allfather choose for him?"

"Executioner" replied the old Wolf.

I would like to think that the "heir" would've been Sanguinius, since Horus himself said that Sanguinius had "the vision and strength strength to carry us to victory, and the wisdom to rule once victory is won." . The one to fortify the defenses would've been Perturabo as his forte was. The guardian of the hearth would've been Dorn, as he was the Emperor's Praetorian. The one to guard the perimeter would've been Guilliman or Corax. The commander of the armies obviously would've been Horus and the intelligence masters would've been Alpharius and/or Omegon. Too bad there was little info for the other thirteen primarchs.

At least that's the way i see it.