Iago and Emilia are on the same boat as Desdemona.
Othello and Desdemona are deeply in love with each other, even though they are very different. Othello has led a life of adventure; Desdemona has hardly been outside her house. Othello is middle-aged; Desdemona is in he late teens or early twenties. Othello is a foreigner who has won his place by merit; Desdemona is from an important Venetian family and has her social status by birth. Othello is dark-skinned; Desdemona is pale. Othello is also very humble, which makes him feel that he is unwarrantably lucky to have the love of a woman like Desdemona. This virtue should enhance their relationship, but it is unfortunately also the chink in Othello's armour through which Iago attacks, making Othello feel that Desdemona must also consider him unworthy of her love.
Emilia.
Emilia is an earthy contrast to the romantic Desdemona.
Two, Desdemona and Emilia.
Iago and Emilia.
Emilia overhears Othello and Desdemona discussing Cassio. Desdemona is pleading on Cassio's behalf to Othello, hoping to persuade him to reinstate Cassio as his lieutenant. In the conversation, Desdemona is trying to help Cassio regain his position in Othello's esteem.
He sees her as Desdemona's friend and thinks she will know the truth.
Desdemona, Othello, Emilia and Roderigo.
Roderigo
Desdemona goes to Lago for advice about what to do about Othello's accusations. This is when Othello asks Emilia to go and find Desdemona while accusing her of harlotry.
The one carrying Desdemona, Emilia and Iago.