
Lysander is the play's representative of earnest romantic love — the young man who actually means what he says, until magic demonstrates that meaning it is no guarantee of its permanence. His enchanted transfer of affection from Hermia to Helena is the play's central demonstration that love's content and love's form are more separable than lovers like to think.
Lysander is the young Athenian whom Hermia loves and who returns her love with evident sincerity at the play's opening — he argues his case before Theseus with warmth and some wit, and his plan to elope through the forest is practical and decisive. He is, at this point, the play's most straightforwardly romantic figure: a young man in love, prepared to act on it.
The enchantment strips this sincerity away in an instant. Waking beside Helena after Puck has applied the love-juice, Lysander transfers his entire emotional vocabulary — every declaration, every protestation, every ardent pursuit — to a new object without any apparent awareness that something has changed. The comedy of his enchanted state is partly the comedy of romantic language itself: the speeches sound identical whether they are addressed to the right woman or the wrong one.
His restored love for Hermia at the play's end is presented as genuine and complete, though the ease with which it was replaced — and then restored — has been noted by critics as the play's most unsentimental observation about romantic constancy. Lysander does not notice the irony. The play invites the audience to.
Lysander is motivated by genuine love for Hermia and a willingness to act on it against social and legal obstacle. Under enchantment he is motivated by the same intensity directed at a different object, which the play suggests is not a different motivation at all.
Lysander is the play's least individually characterised of the four lovers — he is defined primarily by his love for Hermia and then by its enchanted redirection. This is not a weakness in the characterisation so much as a structural point: his interchangeability with Demetrius under the enchantment is one of the play's arguments about the nature of romantic love. He is earnest, capable, and ultimately the most fungible of the four lovers, which is entirely the play's point.