to change sides or loyalties; to become a renegade
to act evasively or equivocally
Wyatt was examined again and again, and wavered and tergiversated a good deal — Charlotte M Yonge
tergiversation /-ʹsaysh(ə)n/ noun
tergiversator noun
[Latin tergiversatus, past part. of tergiversari to turn the back, shuffle, from tergum back + versare: see versatile]