Artic_Rival
Lurker
You forgot personal assistants. Although Phillip was half of W, he sometimes was more of an assistant-type character. Ankh and Kengo and examples of this.
Ankh to me seemed to be more of a dark inversion of Phillip, where as Phillip was more easy going towards Shotaro and selfless, Ankh on the other hand was initially rough towards Eiji and was at first selfish.
Kengo last I saw him was going down this same route, but I assume he's going to be a reconstruction, where it acknowledges the concept of a jerkass partner, and works a way to make it more like what Phillip was.