The legal battle between Lyft and its former COO is shaping up to be a long, ugly fight. The on-demand car company has accused Travis VanderZanden of stealing tens of thousands of secret company documents before he joined Lyft's main competitor, Uber. Now VanderZanden has fired back in a new court filing, saying he was plotting with Lyft's board of directors to dispose of the company's CEO before leaving the startup.