Let me tell you Aesop's Fable about the Lion and the Mouse.
Once upon a time Rengar stepped on a thorn which gave him minor discomfort.
Teemo, being a little trooper, and being aware of such minor things because of his abilities as a scout, and on the same team as Rengar decided to pull it out for him.
Being an absolute card however, Rengar doesn't notice Teemo and the little runt causes more pain trying to pull it out than Rengar could've ever cared for if the thorn was just stuck in his foot.
Rengar has a naturally defensive reaction to this sudden sting in his foot and proceeds to turn around ferociously and instantly decapitate whatever was causing the irritance.
"An Ally has been slain"
"Oops", muttered Rengar as a grin slyly spreads across his face, feeling not remorse, but accomplishment at what he had just done.
MORAL OF THE STORY:
Teemo dies. Good things really do happen.