Originally Posted by cherokeesam
The guard was an actual guard earlier in the movie.....when Frigga dies, that guard actually comes to Loki's cell. That's the same guard that Loki disguises himself as when he's goofing with Thor, and again when he deceives Odin. So I'm assuming that's a recognized guard, some kind of royal steward or chamberlain or something who has cache with both Frigga and Odin, and who cares enough about Loki to sneak down to the dungeon to inform him of Frigga's death.
And I don't think Odin is "absent" from Asgard in any fashion. He's flat out dead, and I think that's the worst use of off-screen action in the MCU to date. Anthony Hopkins and Alan Taylor specifically confirmed that Odin is dead in an interview over on CBM; Feige is a little more elusive about it.
Anthony Hopkins was just having a bad day I bet lol