As he is a hidden monster, So Sorry is a convoluted monster. He’s difficult to find, only existing under certain conditions. In such a case, he is a creature of the void as well as Gaster. He isn’t exempt from the Hunger, though, and summoning him at this point is suicide. Anyone foolish enough to summon him into existence 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.