After years of no food and magic, he is suffering from overwhelming boredom. He loves psychological humor and torture. He suffers from retrograde amnesia and rapid mood swings. Others have a hard time trusting sans due to his worsening psychosis. He also causes monsters to explode through a newly discovered power (likely to his osteokinesis)Despite his psychosis, he still seems to have a defined moral compass, refusing to eat Aliza despite being starved for 7 years until he eventually breaks.