Lina

A 12-year-old girl who lives with her grandmother, Sheryl.

Lina found Vash one day when she was coming home from getting groceries. Seeing the state he was in, she asked him if he was alright. She brought him home, where her grandmother Sheryl cared for Vash.

In Trigun Maximum and in the first anime, Vash lived with her for two years after the Fifth Moon Incident, in Trigun Stampede it was after the Lost July incident.

(Source: Trigun Wiki)