In the first draft teleplay, Kartan was the man who flew his ship into Deneva's sun, to destroy the creatures. Aurelan (who in this draft was not Kirk's sister-in-law) was in love with him, before he died. (The Star Trek Compendium, p. 65)
In the 2nd revised final draft script of "Operation -- Annihilate!", Kartan was described as "A handsome young man, a Denevan, but his face is transformed by agony."