Speaking of the frenemy aspect, in Clarke's introduction to Clarke-branded "Venus Prime" (which Clarke didn't write), he writes:

> It is also an interesting challenge combining the two genres of crime and science fiction, especially as some experts have claimed that it’s impossible. (My sole contribution here is ‘‘Trouble with Time’’; and though I hate to say so, Isaac What’s-His-Name managed it superbly in his Caves of Steel series.)

Which made me chuckle.