Dear an ADC against a Vayne

Chances are you are stronger early. I was playing Thresh with a Trist against a Vayne/Sona and we we getting out pushed and farmed WITHOUT getting ganked. This Trsit would not leave tower and just let Vayne free farm. Never harassed, backed with full HP and mana., and never left tower. Didn't do anything but let vayne free farm. I didn't even bother trying to land a hook just the few times I did she didn't do anything til I was nearly dead and used her rocket jump into them.