Kein happens to be an optimistic and gentle person, reassuring the Doctor and encouraging them to continue their research. They also comment on wishing to help the Doctor gather supplies despite their frail body. However, as the curse begins to take over, their personality is affected as well. Kein becomes more passive-aggressive and bitter about their situation. Sometimes they ask the doctor why they bothered talking to Kein "now". They express a fear for their life and what the curse could do.