Hm. How his character became a tiddy tiger. I mean, magic is mostly his only route, especially since he usually correctly starts off with a male character. But otherwise, I have a few dumb ideas that of course all require a great deal of suspension of disbelief.
- spiderman style, he gets bit by a strange looking cat. Maybe he was being a good guy and saving it from some situation like being hurt by assholes, or it is out in the rain.
-in a similar vein, he encounters some feline goddess that looks like an ordinary cat and she rewards him for treating her or other cats kindly, or speaking well of them. Or is messing with him when he insults her or something.
-anthros existed long ago and a few humans have some of their dna from long ago interbreeding. Lou slowly begins growing fur and a tail, etc and eventually learns that both his parents had some dna, and he inherited enough that it awakened. This of course ignores that dna does not work that way but whatever.
- I asked my sister, whom I often tell stories of Lou, if she could come up with any story ideas of him turning into a big tiddy tiger. She just said an active imagination. So I spun this into a character that is bullied relentlessly by a gang of stupid assholes that is named some variation of kiwi farms. The months go by, his desperation rises. He wishes so hard to be strong enough to fight for himself, terrifying yet beautiful. Like a tiger, or a hero like Wonder Woman. He imagines himself tearing them to shreds with sharp claws. One day he notices some whiskers sprouting from his cheeks. He looks closely at his arms, they have orange fur! His depression is lifting, being replaced not by a desire for revenge, but a growing indifference to the scum that has tormented him for so long. He has a life to live, and he will put a stop to it once and for all, then look to the future. He has transformed himself both physically and mentally through sheer willpower.
- Avatar, basically. Either the separate planet thing where humans can't survive on the surface, or though the destructive behaviors of humanity earth has become unlivable to humans. Many are fleeing, but many don't wish to leave the familiarity of home. They have the option to transfer their minds into the body of a nonhuman creature created for this purpose. They can withstand the lethal conditions human greed has wrought. Lou chooses one with big boobs.
- Lou is kidnapped by evil somebodies. Perhaps us. They conduct experiments on him. One has the unintended consequence of turning him into a powerful anthropomorphic tiger. Other victims are turned into other animals. He is the strongest and eventually he cannot be contained. He breaks out, frees his comrades and escapes.
- he becomes terribly ill from diabetes. He is dying, and undertale larper can't bear it and goes on an epic quest to find him a cure. The cure works but turns him into a tiger. Alternatively undertale larper is the sick one. Lou searches for answers, finds a spell/being that can cure him, but the price is Lou's humanity. Lou is a good friend who would do anything and agrees. He is turned into a beast but it's one that walks upright and has big boobs.
I give Lou permission to use any of these.