As he is a hidden monster, So Sorry is a convoluted monster. He’s difficult to find, only existing under certain conditions, and by definition is a creature of the Void, similar to Glyde and Gaster. He isn’t exempt from the Hunger, though, returning to the Underground to check on his art club far too often, and summoning him at this point is suicide. Anyone foolish enough to summon him into existence, hopeful of the easy prey he once was, had best make their last wishes, as he is starving and insatiable.
There are no more apologies, drawings, or hats from this beast. All he knows is the need to feed.