You can revive Gremio:
You have too collect all
caracters, and die with Pahn in battle with Teo,
before you go to Shasarazade, after killing Boss, and Sonya Shulen, Leknaat should appeard and revive Gremio.
I didn't really tried this but I think It`ll work!
If you have trouble finding all characters:
Just look the Secret paths in the Cave of Wind, you should find Window Crystal for Window of course, and Crowley the Mazus`s (Magician in Suikoden 2)
Added by: DoomedSummoner Oct 1st 2003, ID#10538