Sebastian and Antonio are introduced. Sebastian fears Viola is dead and plans to travel to Orsino's court. Antonio insists on following him despite the danger.
Sebastian is on the coast of Illyria with Antonio, the sea captain who rescued him from the shipwreck. Sebastian reveals that his sister drowned and that he is devastated. He plans to travel to Orsino's court. Antonio offers to come as his servant. Sebastian refuses: Antonio has enemies in Orsino's world and accompanying him would be dangerous. He asks Antonio to take care of himself and says goodbye.
Sebastian leaves. Antonio, alone, acknowledges the danger waiting for him in Illyria but states that he will follow Sebastian regardless.
This scene mirrors Scene 2 of Act 1 but inverts it: where Viola believes Sebastian is dead, here Sebastian believes Viola is dead. Both twins grieve the other; neither knows the other survived. The symmetry is deliberate and prepares the audience for the recognition that cannot happen until Act 5.
Antonio's devotion is established immediately and with intensity. His final line, "But come what may, I do adore thee so / That danger shall seem sport, and I will go," states the feeling plainly: the risk is real and worth it. He speaks of love and jealousy (in the sense of anxious care) as his reasons for refusing to let Sebastian go alone. His language throughout the scene goes beyond ordinary friendship. Whether Shakespeare intends a romantic dimension or simply the intensity of deep loyalty, Antonio's feeling for Sebastian is presented as the most unconditional devotion in the play: he is willing to risk arrest and danger in a city where he is an enemy for the sake of being near him.
Sebastian's response to this devotion is restrained. He is grateful but does not match Antonio's intensity. He says goodbye without great difficulty and leaves. This asymmetry, Antonio's overwhelming feeling set against Sebastian's relative ease, will become more significant when Antonio is arrested in Act 3 believing Sebastian has abandoned him.