Star Trek (ENT): Affliction

[Trinary]

Actually, those ideas people were suggesting concerning Discovery COULD fit into canon.

Think about it - this Augment virus was started because of human DNA mixing with Klingon DNA, resulting not just in a potential change in behavior, but of full-on appearance. Given how T'Kuvma and his branch were all about genetic purity and trying to be the most Klingon of Klingon, I could totally see the Empire fragmenting as a result of the virus spreading and enough Klingons going to war with one another over how pure or not pure they are, with the leadership of all the houses trying to keep themselves pure and even overcompensating for it in their appearances.

However, many Klingons still look the way they do and after what L'Ress pulls, more human-looking Klingons come out of the woodwork to take the Empire for themselves thanks to the chaos her little blackmail causes - or that the human-looking Klingons, to prove they're still Klingon, become the frontline soldiers of the war and expansion effort while the leadership in all their "purity" remain hidden.

That reminds me a bit of Babylon 5 with the Minbari trying to cover up the revelations surrounding Valen/Sinclair's introduction of human DNA into their genepool.