Boredom.

There were no birds here, at least none that she could hear. There were no insects either. This deafening silence was only broken by the rustling of leaves in the breeze and the distant flow of a brook deeper into the forest. Her eyes dully counted the fragments of metal and stone that once composed one of the walls of her now ruined home, feeling as though her mind was about to give in to the deepest states of boredom at any moment. Quarantine, he called it. One hundred years away from one's people is enough time to catch and deal with diseases that the others haven't, and the same goes the other way around. "Aren't you just putting me in time-out for shooting at you with my second metacarpal?" She had questioned then, and with his only response being a shite-eating grin, the more she's certain of it with each passing minute. Tick, tock, tick, tock... And she finally loses it. She taps the rotten wooden planks a couple of times and uses the tip of her good hoof to carve a few simple sigils onto it, conjuring forth a small burst of psionic energies. Floating sigils of red and purple appear all over the wooden flooring, intricate symbols of psionic nature becoming more complex as they swirled and finally fell into place. A bubble formed of nearly-invisible hexagons came into existence around the mare, and so was she encapsulated in an energy shield. The glyphs vanished and the shield turned fully invisible. She had only been inside for five minutes and was already going against his will. Just like the old times. With a large smile, the mare rose to her hooves and joyfully left her home to explore the ruins and find the seven other survivors.