Re: Why was there never a major Romulan character in a Star Trek TV sh
Saavik was originally in TWOK, but that was later retconned in TSFS and TVH in favour of making her full Vulcan.
I don't think there's anything on-screen that would contradict her being half-Romulan.
"...the most elementary and valuable statement in science, the beginning of wisdom, is I do not know." - Lt. Commander Data, "Where Silence Has Lease"