I have a colonist that is Vengeful and has been fine with no debuffs until about a year in we got a raid that included his Grandmother. Once he killed her I suddenly got the "My Rivals are alive -20" debuff. Looking at his social tabs he has no rivals.

He lives alone with his Wife (+100). The only people in his social tab are his now dead grandmother (+15), his father (0) and his brother(+20), both of which are members of other factions. His father has a -50 opinion of my colonist because he is part of a rival faction but my Colonist doesn't consider him a rival. And even if he did, he never had a problem before the raid happened and he killed his grandma. Now I'm stuck with a permanent -20!

Please help!