Reddit reviews Jingo: A Novel of Discworld

They're talking about the relationship between Leonard of Quirm and Lord Vetinari.

These two feature in quite a few of the Discworld novels, but chiefly it would be in:

Wyrd Sisters
Men at Arms
Jingo
The Fifth Elephant
The Last Hero

All Amazon-linked for your convenience. ;)

Jingo is such a fun word to use. I learned it from Terry Pratchett. It's like patriotic, but with negative and militant connotations. Actually pretty useful these days.