I wrote this one for Jon Ford, when he lost his first character because of an imposter and there was some question as to whether he was even really himself.
The rhyme scheme is one of my favorites: ABCB. The meter is rather interesting because it alternates. Even-numbered lines are proper iambic pentameter, but odd-numbered lines are missing the first syllable, and start with a stressed rather than unstressed one.
You can also read the odd-numbered lines with stress on only the first and fifth syllables, and the even-numbered ones with stress only on the second and sixth. That is actually my preferred form.