Star Wars Insider 130, The Tenebrous Way

Admist the billions upon billions of individual midi-chlorian deaths in Tenebrous' cells were a tiny fraction of midi-chlorians that were not dying. That would not die so long as they inhabited a living host. These especially tenacious midi-chlorians - Tenebrous had privately labeled them with the jesting sobriquet maxi-clorians - had been altered. Improved. It would not be an overstatement, in Tenebrous' opinion, to use the word perfected. These maxi-chlorians would indeed migrate, but not into the Force.

They would migrate into Plagueis.

[...]

Beside Tenebrous' corpse, as Plagueis carefully observed the vanishing of Tenebrous' midi-chlorians, maxi-chlorians were being subtly and invisibly carried across the intervening space to settle in Plagueis' eyes and mouth, on his skin and into an open wound on his back, where they entered the apprentice's bloodstream and slipped into his cells, releasing their vital cargo of Tenebrous' mind.

Perfect. And what made it more parfect was that his apprentice would never comprehend the ironic pun of the name Tenebrous had given him: Plagueis.

The diseased one.

Driven by the dark side-powered will of the Sith Master, the retrovirus propagated with incredible speed. As it carried his consciousness throughout his apprentice's body, Tenebrous found himself becoming pleasurably aware that he was gaining access to Plagueis' sensorium. He could literally feel what Plagueis felt, both the coldly clinical satisfaction at having successfully engineered Tenebrous' murder... and the Force-perception that let PLagueis monitor the last vanishing remnants of Tenebrous' uninfected midi-chlorians.

Full access to his apprentice's Force-perceptions! Delightful.

[...]

The searing truth was driven home by the gathering darkness that gathered his clouded foresight. Soon all he could see of the future was a hazy smear of shadow... as the retrovirus he had become infected Plagueis' every cell. The retrovirus he had allowed to sacrifice his ability to gaze forward in time... and had thus robbed his apprentice of his power to sense the future.

Which would seal his own doom as well.

His single-minded pursuit of eternal life and supreme power had accomplished only this. He would be destroyed by his own triumph.

Now wholly giving himself over to panic, Tenebrous turned his will upon undoing the damage he had done. With all his multiplied power, he yanked his maxi-chlorians back out from Plagueis' body in a spray of Force energy from his eyes, his mouth, the wound, and every other cell.

- Star Wars Insider 130, The Tenebrous Way