In HPMOR, there is no strong reason to think Voldemort is a disembodied spirit that needs to possess someone, rather than being and always having been embodied in the body currently known as Quirrel. I wouldn’t give your estimated 15% to even the entire probability that hpmor!Voldie can or needs to posess anyone.
While this may be true, it would be a large departure from canon. To postulate such a large departure from canon, we need a certain amount of evidence. The amount of evidence on that subject does not seem high to me. I give a ~60% chance that Voldemort is/was at some point a disembodied spirit. (Here is my PredictionBook prediction on the subject.)
In HPMOR, there is no strong reason to think Voldemort is a disembodied spirit that needs to possess someone, rather than being and always having been embodied in the body currently known as Quirrel. I wouldn’t give your estimated 15% to even the entire probability that hpmor!Voldie can or needs to posess anyone.
While this may be true, it would be a large departure from canon. To postulate such a large departure from canon, we need a certain amount of evidence. The amount of evidence on that subject does not seem high to me. I give a ~60% chance that Voldemort is/was at some point a disembodied spirit. (Here is my PredictionBook prediction on the subject.)