In my DB:NA storyline, Vegeta has a twin brother named Rigor. Rigor was seperated from Vegeta at a very young age and sent to the war planet Yelna. While there, his tail was cut off. However, it was surgically replaced after Rigor reached Super Saiyan 4 at age 12. The tail kept Rigor's power under wraps. When Rigor and his saiyan wife Separi were banished from Yelna, Rigor destroyed it. When Rigor and Separi landed on Earth, Rigor attempted to kill Vegeta to prove he was the superior brother. During the course of battle, the Super warriors (Goku, Gohan, Goten, Trunks, 18, Pan, and Piccolo) joined the fray, and Rigor became enraged when Goku and Vegeta seemed to be able to match his power. It was with that that Rigor ascended and became Super Saiyan 5. Though incredibly powerful, the SS5 transformation was incredibly taxing on Rigor's body, much like Goku's Kaio-Ken. Rigor seemed to be ready to annihilate the super warriors when Goku and Vegeta merged to become SS4 Gogeta. Armed with the fusion and a 20X Kaio-Ken, Gogeta defeated Rigor after the SS5 transformation wore off. Defeated, Rigor left Earth with Separi, vowing to return. When he did, well... I'll tell you later!!