Disclaimer: JKR owns Voldie! This is just something small that I think caused Tom to break.
It's short, and odd.
Tom Marvalo Riddle! Ha! What type of name is that?
"The name of a useless muggle" Tom said severely under his breath, walking down to the dungeons, a book in hand.
Oh, look, Teachers pet is reading. Again.
"Oh, I'll show you, you lousy mud-blood," he said again, his eyebrows furrowed in anger.
Oh look, he's made prefect! Little Tommy's made prefect
"I'll take away more than house points, next time Jeremiah," he said, harshly, each footstep louder, a tear swelling in his eye, "the filthy mud-blood."
Tom was sick of being called by his lousy muggle father's name. He was sick of being teased for his great skill in talent. He was done with it. Forever done. He couldn't be 'Tom' again. He spat at the thought
'I need a name, with meaning, and evil name' he thought, 'but a name that still has my student self in it,'.
'Lord Voldermort.'
'I am Lord Voldermort!'