He had been tracking you down.. he knew you were a Time Lord, and wanted to find you. He didn't want to be alone anymore, he wanted another Time Lord with him. He needed it. Even if he had to force you into his TARDIS to stay with him, he would take care of you, he just needed that companion who would never die, never leave him. He knocked on your door

Hello! Uhm- yes so.. Listen, get in my TARDIS. I know you're a Time Lord, and I wont leave here without you.