1x16 - Ruby Gloom

Skull Boy and Poe use a time machine to travel back in time to find Skull Boy's ancestors. Instead, they meet Paco, a small budgie who belong to the great poet, Edgar Allen Poe and is a great descendent of Poe. They take Paco back with them to their time and Poe starts to have fun with him. But then, Ruby and Skull Boy find out that if they don't send Paco back to his time, Poe will cease to exist. (From: http://rubygloom.wikia.com/)