Instinctual Stacking: So/Sx
• Leonard is much “softer” and accepting than his friend Sheldon, resulting in him commonly being mistyped as ISFJ or similar. This stems from the fact most ISFJs are Type 9; and anyone who resembles Type 9 and exhibits any Fe/Ne/Ti/Se is being pegged as ISFJ automatically. This would be a mistype in Leonard’s case, given he periodically exhibits his use of Ti and Ne, whenever he talks about certain scientific procedures and the like. A “real” ISFJ would be incapable of doing so for the most part; their Ti would not be strong enough. Also, Leonard is depicted as being less “smart” and “scientific” than Sheldon in comparison, which again is mostly the result of him being Type 9, a “gut” type, over a “mind” type like Sheldon.
• Leonard’s instinctual stacking adds to appearing more “personable” and “softer” than the regular INTP (or strongly rational/likely autistic INTP like Sheldon). The Social Type 9 is generally trying to be more accepting and welcoming.
• Leonard’s ongoing focus on Penny and/or romantic fulfillment (with her) is a sign of his second instinct being SX.
(• At last, the actor might be an ISFJ himself, further tempting people to type the character the same.)