I believe I make a reference in the HC text of a story told to Razix by a cousin I think it was. Raz in HC comes from a large family, many of whom are pilots in the Union. So in my mind, the Razix in The Cassini Mission is a distant relative of his.
Their personalities are different as well. Razix in HC is more playful.
(Truthfully, I re-purposed the name and thought I’d spelled it Razyx in the book, but didn’t realize it was the same until I was working on Zed’s story.)