R&J Devices 7

Alliteration
"One of our order, to associate me" (V.ii.7).
The vowel sound O is repeated to speed up the flow of this line.

Paradox 
"Unhappy fortune! By my brother head"(V.ii.18).
Fortune is normally happy not unhappy,

Motif 
"Unhappy fortune! By my brother head"(V.ii.18).
This line is an example of the recurring idea of destiny fortune and fate.