I have no clue which one is older but I'm settling on Tirek. I had a headcanon once upon a book I'm never gonna finish that minatours/humanoid creatures come from a far off land. I like to think Tirek and Scorpan were like royal brothers there and set out to find more land...by tyranny.
Yay for making villains sappy.
Eh, maybe they did love each other at one point in their lives. Who knows. Who needs love when you have free ranged pony/spirit of chaos magic?