So for the first time I'm doing the Empire side of the Civil War after escaping Helgen with Ralof.

I just did the Jagged Crown quest and couldn't help but notice that Hadvar wasn't there. Always in the past the person I escaped with was in the group on that quest, but this time, I suppose since I escaped with Ralof, Hadvar isn't there at all. I had just assumed he would be there and just say something like "Oh, I remember you" or something. But he's gone.

So, is he dead? Does he show up later (like on the Compelling Tribute quest)?

Thanks.

Hadvar will show up later in the questline.
If you escape with Ralof but join the Empire, Hadvar won't show up until after the Jagged Crown the reverse is also true.