O my poor brother, and so perchance may he be (1.2.7)
Assure yourself, after our ship did split, When you and those poor number saved with you, Hung on our driving boat, I saw your brother (1.2.9-12)
My father has talked about him! I shall work for him!
ACT 1, SCENE 2
In this land of Illyria, what is here for me?
Who is this Noble Duke?
Be you his eunuch, and your mute I’ll be. When my tongue blabs, then let mine eyes not see. (1.2.65-66)
There's a lot of things here in Illyria. For it is ruled by a noble Duke.
Orsino
Viola and her twin brother, Sebastian, were part of a voyage but their ship encountered an accident resulting in Viola splitting from her brother.
ACT 1, SCENE 1
"If music be the food of love, play on." (2.1.1)
Viola and the Captain found themselves ashore at Illyria's beaches. Viola is worried her brother Sebastian didn't survive the ship wreck but the Captain assured her he is find.
ACT 1, SCENE 4
I trust you wholeheartedly Cesario, so I order for you to show my love to the one and only Lady Olivia.
The captain tells her about Illyria and the Duke who rules the land. Viola grew curious of the Duke and wants to work for him as an eunuch.
ACT 1, SCENE 4
Viola, now Cesario, works for Duke Orsino as his eunuch. Cesario plays music as the Duke waits impatiently for Lady Olivia to reciprocate his love.
Of course Sir
Cesario becomes close with the Duke enough for the Duke to entrust him as a messenger to Lady Olivia to show the Duke's love for her.
Do you think she'll let me in noble one?
Cesario was hurt deep down because she, Viola, fell in love with Duke Orsino. But, Ceasrio still followed the Duke's instructions and went to woo Lady Olivia.