The smartest and quirkiest of the Stones is also the only one who isn't known to be immune to the zombie virus, but that doesn't diminish her importance in the slightest. In her siblings' eyes, it makes her the most important.
As part of the rebellion against the government, Lilah Stone has proven her usefulness time and time again, helping provide fresh vegetables and fruit via the greenhouses she tends, as well as experiments in the laboratory, which involve explosives and testing various hypotheses on zombies.
Your brother and sisters miss you, Lemondrop! Please come back!