Vita in The Manga
The two manga series each add a number of short chapters that supplement the latter two anime series. These chapters details the actions and thoughts of various characters at different points before, during or after the anime series.
Vita is still short teenager, living with Hayate. It has been mentioned in the manga, however, that she may use transformation magic to appear higher. She even notes that despite appearing to be a child,she plays croquet with (partly as a pretext for getting out of the house and hunting Linker Cores).
Vita is at times haunted by memories of a mission that she and Nanoha participated in that nearly ended in the death of Nanoha. In the TV series, episode 9 of StrikerS, it is explained that it happened two years after the winter when she joined the Bureau. Vita and Nanoha were on a recon mission when an unknown unit attacked them. While the unit was weak enough for Nanoha to easily defeat, the strain she had put on her body caused her to slow down, and she was severely wounded. Nanoha was thought to be unable to walk or fly again, but eventually recovered. As a result, Vita often becomes uncomfortable when seeing things that remind her of the incident, particularly gadgets with legs.
Read more about this topic: Vita (Nanoha)