After taking in so much magic from Runeterra's leighlines, after making contact with the Void in an attempt to harness its power, it was a miracle that Veigar was alive, that his body could handle the change, first to the size of Nasus from the influence of an arcanely activated latent Rage Gene. But the Tiny Master hadn't stopped there, heavens no! Consuming and glutting on the Magic like a leech on an artery, trying so hard to fill in the emptiness that the Void's power left within him, a drive that yordles normally filled with warmth and comfort and love, things that a Monster like himself didn't deserve. Fill it with blood, with Magic, with chaos and death and destruction, because for the longest time he wasn't ever able to get his hands on anything else. Until that stubborn, heroic Badger kept shoving it in his face that is.
By the time the Institute could drain the Magic from the arcanely conductive Mage, Veigar could have stood on all fours and slapped Baron Nashor in the face, covered in spines, sprouting wings and a tail, all things that served to make him look more horrific, more like the Monster that everyone painted him out to be. It was a miracle he was alive, a miracle that the dark furred yordle immediately wished didn't happen.
Now all the features that made other yordles consider him a Creature, a Monster were accentuated! Bigger fangs that hung out of his lips, claws thicker, bigger and even more wickedly curved than before, wings, a tail---it was a nightmare! All his life he wanted nothing more than to be loved, to be accepted, turning his sights to the rest of Valoran when Bandle City, when the supposedly most amicable race out there, couldn't provide that. There was no way he could hide himself away now, he was HIDEOUS! Even Lulu wouldn't be able to look past those things, even the heroic Teemo would cringe and run away from him.
"I...I didn't ask for this! I didn't ask for this! I---I---AAAAOOOO!!! Aaaoooooo!!"
And then came those long, sorrowful cries, begging the world WHY? WHY? Why him!? What did he do! Why him? Why couldn't he have friends? Why couldn't he have love and warmth like everyone else? Why couldn't be accepted? Why did the world feel the need to constantly take a dump on him!? He felt Teemo's hand on his shoulder, but was inconsolable, knowing how much worse things were going to be now that he looked even more freakish, more monstrous, more demonic! How...how could he ever hope to be accepted now?