Well I was thinking that Raz saved Bran's life somehow, and that's why Branigan owes him his life and is 1st Lieutenant of Wraithguard.
They couldn't really have been childhood friends, because Branigan is a little over 400 years old (I've already told this to a few people in-game although I haven't given a specific age yet). Even if Razael was very old, 100 years old or so, before he became Scourge (I think all Forsaken were Scourge first-- if not, then MOST of them were), Branigan would have been around 300 years old when Raz was born.
Actually I just realized something. Raz could have been resurrected as Scourge. Meaning he could have been alive even thousands of years ago-- he would just have been genuinely dead most of that time until Year 21-29. The Burning Legion didn't take just the newly dead (into the Scourge), they reanimated the bodies of those buried under the ground as well.
Although, thinking about it again, he couldn't have been dead for TOO long, or else his body would have been completely decomposed. (Once reanimated the bodies stop decomposing but reanimation doesn't "fix" what happened in the grave.)
So how long do dead bodies "last"?