"First came the dark all went black-silent. The world-reality I knew and hated-despised ended. Cold-freezing and afraid I heard a voice. Not the voice of the-the Great Horned Rat. Great Horned Rat hated-despised me yes-yes. Would have been murder-killed if not for luck-fate... Voice... kind-gentler, nicer-sweeter. The Great-Furred-Rat, it called-deemed itself. Said I was-is one of few-few rat-kin to know right-right from wrong-wrong. Demanded I worship-served. I agreed, and I was shove-thrusted into new world...? No-no. World-world isnt right. Reality? Im not sure-sure Yes-Yes. Awoke on shuttle-ship... It only had-wanted one thing of me. My blood-blood, and to persist-survive. I will not die-perish. I mustn't."
Finally made a board for my skaven! Been thinking about how to make his lore. It was decided that at the end of the "end times" in Warhammer Fantasy, when the world/universe was gone, he was thrown into SS14 via warp/winds of magic/godly/bluespace/anomaly shinanigans. Made a thing called the "Great Furred Rat" that's a chaotic, neutral version of the great horned rat, that just wants its followers to live and donate their blood to alter. Weird, I know, but I'm not great at coming up with lore that big. 
He was turned into a rodentia, but still has the mannerisms of a skaven, and due to his time in this new environment, he's become significantly less unghinged, and his current good qualities that were nearly beat out of him in skaven society have flourished.
But some of skaven society cant be fully be left behind. Violence is in his blood, and he is quick to attack anyone who harms someone he deems "part of his clan" or "circle of friend-pals™.
