who is rishi?

Rishi is the younger brother of Sameer Diwan & the son of Diwan builders. He left his family & went to the US. It is not as yet shown clearly whats his connection to Vidhit...but he might be his friend in the US. No details have as yet been shown regarding vidhit...but at present he his hospitalized & will be well enough to be able to come back to India in a month. as to y is rishi helping indira...no reason has as yet been shown in the show.