German C2 · Subtleties of the Subjunctive
Konjunktiv I vs. Konjunktiv II in der indirekten Rede – C2 German Grammar
In careful written German, Konjunktiv I marks neutral reported speech ("er sagt, er komme"), while Konjunktiv II often hints at the speaker's doubt about the claim ("er sagt, er käme" sounds more skeptical).