Tommy Maximoff is a mutant who calls himself Speed.
As Tommy Maximoff
Originally, he was a soul shard of the demon Mephisto and borne to Wanda Maximoff and Vision with his brother Billy Maximoff. They were supposedly disposed of by Agatha Harkness when their true nature was discovered. In reality, they were reincarenated into Thomas Shepherd and William Kaplan.
Thomas 'Tommy' Shepherd was reborn as the only son of Frank and Mary Shepherd in Springfield, New Jersey. Frank and Mary divorced when Thomas was young and he was in between juvenile halls for majority of his life. In one detention hall, he had a brief relationship with a girl named Lisa.
His mutant powers manifested when he 'accidently' vaporized his school. As a result, Thomas was imprisoned in a facility which dampened his powers. He had locked up, exprimented on, and tested for months to be used as a living weapon until he was freed by the Young Avengers.
After Hulkling was captured by the Kree sentries, Wiccan and the other Young Avengers were desparate to rescue him. The Vision reccomended using the Avengers Fail-Safe Program to locate reinforcements. The team was able to locate him a high security dention center for super-powered juveniles. They release him from their cell and afterwards, Stature looks at both Thomas and William and discovers the possiblility that they could be twins.
After the battle, Thomas officially joined the young Avengers under the codename 'Speed'. He was anxious to be a superhero and was the first to alert the Young Avengers team that the Zodiac was attacking the United Nations.