As soon as a Police Box was spotted flying into Gallifrey's atmosphere, Koschei knew his friend had answered his call. And he knew exactly where to find him too. Back at the beginning, where their paths had first split. The mountainside, of course, but well it was more a memorial of the mountain now. A Dalek shell had hit there and blown the entire site to shreds. The only thing that remained was the lake, now named Lake Selemat, which could only remind Koschei of the adventures he turned down. There at the eighth chime of the clock a police box materialise, right where it was stolen over four hundred years before. It intrigued Koschei by the fact that the chameleon circuit could change the exterior into anything he wanted, so why a police box of all things? Maybe he just liked the colour blue. The doors opened to darkness and Koschei prepared himself because it was very unlikely he would meet the same man he knew as his friend. But Koschei had changed himself, not very dramatically, maybe looking slightly older and with a change of eye colour. Would Theta even recognise him? After travelling so far and seeing so much, it would be easy for Koschei to be...buried underneath it all. A man came into the light, but stayed within the door frame of the TARDIS. It was a different man, but he knew it was still him, it was still Theta.
"Hello, my friend", he smiled, with the memories of the childhood blazing in his new, green eyes. He looked significantly older, with long, chocolate-brown hair past his ears and a slight tan on his cheeks.
"Which regeneration is this then?" Koschei answered.
"Eight".
"What the Hell have you been doing to have seven regenerations in four hundred years?"
"Um...scrapping with monsters".
"So business as normal then? How was the galaxy? Still as amazing as you figured it out to be".
"Nothing without you Koschei. Nothing".
"Actually I wanted to ask you something about that. Can I come with you? Like travelling with you, I'm fed up of soldier business".
"Really, you want to? Yes, yes, of course you can come. It would be fantastic. Hang on, let me get you a key", he said, hurrying inside. A strange whirring came from the TARDIS console, like one of distress, and Theta's head shot up from where he was hunting in his toolbox for a spare key. "What is it? What's wrong, dear?" It let out another pained squeel, then it turned into a materialisation sound as it took off. "No, no. I can't leave him again. Go back, go back now!" he ordered, the rage flooding into his cheeks. "I-I can't leave him again. It'll break him".
:/.
Koschei looked on in horror as the doors slammed in his face and the blue box took off again. He strained back the tears and stormed back off to his camp. In a fit of anger and sadness he collapsed on his bed and just sobbed to himself, the tears running down his cheeks. He didn't mind too much the first time, because he made that choice, but this time. This time he had his hand on his lever and just left. Getting onto his feet, he wiped the tears away and just stood looking at the tattered version of himself in the mirror.
"No more waiting Koschei. No more of the parasite that is Theta Sigma. Kill or cure yourself".