A not-so-good word is used in this, because I honestly couldn't think of one that conveyed the necessary meaning.
I am not a possessive controlling bastard.
I may be an older brother who looks out for his family, but I will not glare down men who express interest in my sisters. Or the woman you've invented to be my "love interest."
Nor will I forbid them to court if they wish.
And I will most certainly not threaten potential suitors with death or duels if they look at, admire, touch, express interest in, converse with, or dance with my sisters or "love interest."
That applies to Caspian too, movie-watchers.