Which character speaks to Dante from the tree in the 2nd ring of the violent?

In the second ring of the violent, Dante encounters Brunetto Latini, who is found among the Sodomites punished for their sins. Latini, a significant figure in Dante’s life and a mentor to him, speaks to Dante from a tree where he is condemned to spend eternity. This interaction is poignant, as it illustrates not only the theme of mentorship and the loss of guidance but also Dante's respect and affection for Latini, despite the circumstances of their meeting. Latini's presence serves to highlight the pain of lost potential, as he reflects on the influence he had on Dante.

The other characters listed do not appear in this specific context within the second ring. Pope Nicholas III is found in a different part of Hell, specifically in the simoniacs’ pit, while Vanni Fucci and Guido da Montefeltro are also placed in distinct areas addressing different sins. Thus, Brunetto Latini is indeed the character who speaks to Dante from the tree in this particular part of Dante's journey through the Inferno.