si quis vestrum iudices
aut eorum qui adsunt
ut defenderim multos
subito nunc mutata voluntate
is, si mei consili causam rationemque cognoverit
et in hac causa profecto
mihi esse actorem putabit.
Periodicity is maintained through anticipation and suspence.
Si quis, of course, suspends the apodosis, but it also suspends the substantive sense of the protasis as a hypothetical.
forte miratur: Insists on the hypothetical and leads to an expectation that the "surprise" will be articulated in some form of O.O.
me qui: the relative suspends the main clause of O.O. Within such a structure, Cicero does not need to rely upon a verb to conclude the subordination, since the sentence will be periodic as long as the audience expects both a main clause in OO. and an eventual apodosis. This allows him easily to bring the verbs defenderim and laeserim into emphatic positions.
subito nunc ... descendere: the O.O. is closed with a verb, which is common in Latin subordinate clause to demarcate closure (Note German; it is an Indo-European phenomenon).
is, si: the apososis is itself immediately suspended thru another protasis.
et... et...: the correlating conjuctions allow the content of the first et to be minimal. Again, Cicero is suspending sense even within the structure of an anticipatory et ... et....
et ... putabit: The period finally reaches closure with a demarcative verb and the emphatic claim (this is what the sentence has suspended up until now) -- "No one but Me."
probabit ... putabit... : Cicero avoids the more flagrant homoeoteleuta available, but does not wholly eschew them. Here, rhythm helps the "rhyme" acheive a sense of closure and appropriateness.