Orignally experemented on by scientists in a lab in Oregen,the bear is now a threat to any that may meet this unworldly creature. The scientists plan before the war was to use it as a wepon,now mind you this was before they even knew that nuclear wepons were being used.They had it's real teeth and claws replaced with steel blades of some sort,hardly fed it so it would always be agressive,and had it put on somesort of steroids.Once the war started everyone abandoned the project and left the bear and other animals left to rot.But some animals lived through the war feasting on their dead conpanions.Once the radaiton from the wepons reached the still living animals and either killed,or streanthend them.Now free the bear now top of the food chain romes the barren ladscape killing whatever it sees.But this might be bad news for the bear as the glowing green scars can be seen from far away and the extra mouths serve no purposs,not to mention the rust forming on the claws and the smell of decay and blood that has stained his fur.Never the less it thrives and if you ever come into contact with this "thing" don't bother running or hiding.Just hope and pray its hawk-like eyes won't see you and it's keen nose doesn't smell you through the icy tundras and plains of our new snowy world.
(idk how nuclear wepons work so yeah + I didn't proofread it so there are alot of spelling errors XD)