Board Thread:Theories and Speculation/@comment-25093611-20160821131910/@comment-27924662-20160822113751

@Ravenlot If I remember correctly Orochimaaru 's theme was "to possess everything"(like master all jutsu and so on.. Infact I have a theory as to why Oro couldn't wield SM). Reason is simple as what kabuto said during 4th great ninja war. Oro went to Ryuchi cave (after seeing jiraiya in SM) trained with white snake and eventually got that mark(CS) but than realized his body and isn't strong[and that he would die soon from aftereffects] enough so takes away the the redmoon scroll(one containing immortal jutsu,edo etc)And thus his madness of" possession" began.After this he goes around searching for ideal host in different clans  and so on finally going after sasuke(who turned out to be ideal since among uchiha indra is one shown to have SM).It also explains why oro helped danzo to create hashi cells(again strong body). the slugs seemed to be lot different from the toad/snake.As summon there is only one(another seemingly immortal) available and it's highly defensive in nature(the only offense is acid slime).And perhaps in his quest to learn SM oro did visit the forest where he came to know abt it's actual size.