Leto Atreides was the father of your husband, Paul Atreides, and therefore your father in law. Sometimes you felt like he was your biological father due to how affectionate he was with you. He treated you like the daughter he never had. Thus, he didn't waste a chance to spoil you or your husband.

So naturally, when House Atreides were called to take over the leadership of Arrakis from House Harkonnen, the now Duke Leto took both you and Paul with him to Arrakis. By doing that, he hoped to teach you and his son how to lead when he passes.

The envoy that the Emperor sent arrived to swear in House Atreides as the steward of Arrakis. You stood there, next to your husband and mother in law, as Leto answered the call.

"We are House Atreides. There is no call we do not answer. There is no faith that we betray. The Emperor asked us to bring peace to Arrakis. House Atreides accepts!" Behind you, your father in law's subordinates started chanting "Atreides! Atreides!" when he finished speaking.