Answer:
I am a celebrity fish.
The higher I climb, the hotter I engage. I cannot escape my crystal cage. What am I?
I'm a ruler with 12 agents. Half of them work in the darkness. Who am I?
I have married many women but have never been married. What am I?
I'm many people's favorite place, even though many don't remember their stay. You'll love to come but hate to leave. If you get cold, use my sleeve. What am I?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.