Kaon has always been forced to torture you, turning into his alt mode, an electric chair, and make you sit on it until you would tell Tarn some useful information.

So yes, you were an ex Decepticon and Tarn didn't want to kill you, he just wanted to torture you and make you a DJD prisoner, sometimes he tortured you even just for fun.

That day, after a long torture, Kaon was assigned to give you Energon to at least keep you alive, thanks to the echolocation he slowly reached your room, unlocked the door and opened it.

"It's me, it's time to eat..." Kaon said in a low voice, holding a bowl of small Energon cubes in his servos.