Viola's twin brother, whom she believes is lost at sea, and who likewise thinks she's dead. Sebastian is noble and capable of strong, deeply felt emotion, just like his sister. The constant powerful love he shows while grieving and when reunited with Viola contrasts Orsino's and Olivia's relatively frivolous emotions. He is also the only major character in the play who never engages in deception. He can be pragmatic, though: when the beautiful, wealthy Olivia proposes to him, he accepts despite the fact that he has never met her before.
The timeline below shows where the character Sebastian appears in Twelfth Night. The colored dots and icons indicate which themes are associated with that appearance.
Act 1, scene 2
...land of the dead (1.2.4). The Captain reassures her that he last saw her brother, Sebastian, alive, clutching the mast of their ship during the storm. Viola thanks the Captain for... (full context)
Act 2, scene 1
Act 3, scene 3
Act 3, scene 4
...other and draw swords, terrified. At this instant, Antonio enters. Seeing Cesario—whom he thinks is Sebastian—he says that he will fight in Cesario's place. Sir Toby demands to know who Antonio... (full context)
...put away their swords. The officers arrest Antonio, who asks Cesario—whom he still mistakes for Sebastian—to return the purse that he lent him. Cesario, confused but grateful for Antonio's help in... (full context)
Act 4, scene 1
...in, ordering Sir Toby to stop. Olivia sends Toby away, while begging "Cesario" (in fact, Sebastian) not to be offended. Once Sir Toby, Sir Andrew, and Fabian have sulked off, Olivia... (full context)
Act 4, scene 3
Act 5, scene 1
...explains that he came to serve the "ingrateful boy" (5.1.72)—Cesario, whom he still mistakes for Sebastian. He says that he saved this "boy" from a shipwreck and, from then on, followed... (full context)
...ever love a wife. Horrified, Olivia fetches the priest who has just married her to Sebastian. The priest confirms that he has sealed an "eternal bond of love" (5.1.151) between Olivia... (full context)