«That you were once unkind befriends me now,
And for that sorrow which I then did feel».
The poet and the youth now are able to appreciate traded injuries, with the poet neglecting the youth for his mistress and the youth committing a vague “trespass.”
That you were once unkind befriends me now,
But their positions are only reversed in a rhetorical sense, for the poet still argues that they remain friends: “But that your trespass now becomes a fee; / Mine ransoms yours, and yours must ransom me.” Sonnet 120 embodies yet another variation on the poet’s transference of roles from sufferer — “And for that sorrow which I then did feel” — to inconstant wrongdoer — “. . . you were by my unkindness shaken” — to tyrant — “And I, a tyrant, have no leisure taken.” The poetic story suddenly becomes complex and tortured by another’s presence, although this presence remains in the background.
English audio from YouTube Channel Socratica
Summary from Cliffsnotes.com