[QUOTE=Snickers]
Grevious wasn’t a droid. He’s one of them there biological/bionic combos, like Darth Vader. After he was gravely injured in some conflict, they put what was left of him in a super suit type thing that enabled his continued survival. (It’s my understanding that he was more gravely injured than Vader, yet put into a far more interesting and advanced get-up than Vader’s that’s also curiously much more vulnerable as well. Weird thing, these retcons.)
God, I’m a geek.
[/QUOTE]
Grievous was a well-known and respected strategist when, erm, alive. Palpatine approached him through Dooku to work for them. He refused. Strangely enough, his shuttle was blown up shortly after. Strangely enough, he was retrieved by a ship that just happened to be there with excellent medical facilities. Strangely enough, after his brain and bits were droided up, he became much more interested in helping out the to be-Emperor.
Look on the bright side; I can still out-geek you. 