Speaker
Like the speaker in the rest of the poems in Browning’s collection entitled Sonnets from the Portuguese, the speaker here is a version of the author. Elizabeth Barrett Browning addressed this and the other poems in the collection to her future husband Robert Browning, who in fact urged her to publish the works. Within the poem itself, however, almost no clues are given as to the speaker's identity. What we can discern is that the speaker is deeply in love, and uses an active imagination to soothe the difficulty of being separated from the object of that love. Moreover, they are pensive and analytical, intrigued by the interplay of imagination and real life.
“Thee”
The "thee" addressed by the speaker is, on a literal level, the poet's husband (and fellow poet) Robert Browning, for whom the poem was first written. Again, however, the actual text of the poem reveals nothing about this autobiographical correspondence. Instead, it tells us that the "thee" is the speaker's lover, and that the two of them are together only sporadically. While the speaker does urge the "thee" to act assertively, it's not entirely clear whether this is a comment on the addressee's personality, or merely a reference to their physical separation.
