Littlepip possessed by a Membrane Parasite, which she came across after diverting from the gang on a trek through the Wastelands. The Membrane Parasite itself may look stupid, hence the vacant expression of our possessed heroine here, but are actually quite intelligent, largely due to them feeding off the brain power of ponies and other creatures. The Membrane Parasite decided to use Littlepip as a puppet after scanning her brain and gaining knowledge of her courage and skill in combat and fading into her head, attaching to her brain
 
Edit by: Me  
Based on an original vector by: dr-phoen-x