Who is Nisha Banerjee from The Lying Game and what is their importance?

Nisha Banerjee is co-captain with Sutton on the tennis team, and the two obviously have problems dating back prior to Emma's arrival. Nisha's mother has died and when Sutton's friends play a prank on her, putting fake blood in her locker, a memento of her mother is ruined. Emma can sense the pain as Nisha tells her about the loss.