Young Tristram (or "Tantrum" as his friends call him) is a little mouse boy who lives in the Metropolis Zone. He has appeared through Sonic the Comic issues 73 to 76 in the Tails story Fox On The Run.
Tails first met Tantrum in the Spring Flower Zone after freeing him from a Buzzer Badnik shell. Alone and a long way from home, Tantrum demanded that Tails take him back to the Metropolis Zone. He didn't help matters along with his constant whining and crying, which would always result in the situation becoming worse.
Tantrum and Tails plunged into a pit whilst trying to escape from Fleabyte, who was after the bounty on Tails's head. The two wound up inside a network of caves, and Tantrum's incessant wailing caused their entrance to collapse, trapping them. Tantrum and Tails were forced to navigate the caves, with the mouse making it harder and harder for Tails to protect him by running at the sight of Badniks, causing a bridge to collapse and struggling whilst Tails tried to fly him to safety. The two managed to escape the caverns, but Fleabyte had managed to track them down and held Tantrum at gunpoint. Tantrum managed to save himself by screaming and causing a rockslide that knocked out Fleabyte. With the bounty hunter defeated, Tails and Tantrum made their escape and Tantrum was returned home to his mother.