Board Thread:General Discussion/@comment-27524978-20160210030742/@comment-43574-20160331192907

To throw in my two cents for the other side as well: A parallel is not the same as an equivalent. Undertale have a lot of parallels to Earthbound/Mother; Flowey, especially his final fight on Neutral, has a of them to Giygas, the Pacifist and Genocide endings also have some (milder) parallels to the endings of Mother 1 and Mother 3 respectively, the Temmies have parallels to the Mister Saturns etc. This obviously doesn't mean Flowey is Giygas, that the Temmies are Mister Saturns or that Chara is Lucas.

On the other hand Sans backstory is left far more ambiguous than that of any of those, he seems to (intentionally or not) concentrate a lot more parallels to himself than anyone else and he is frequently implied to be different from the other monsters without any explanation as to why. So it does leave more room for the possibility.

Ultimately it comes down to whatever you want. If you want Sans to be Ness there is enough room and similarities for you to consider him as such and the inconsistencies are small enough that you can hand-wave them away in any number of ways (Sans was not at Max HP, Earthbound HP and Undertale HP are different things and his attacks *were* PSI attack as attacks in Undertale are more based on things like willpower than they are actual physical damage, etc. etc.). Or if you don't want him to be Ness you can just let a parallel be a parallel. A copy of the Mona-Lisa is after all not itself the Mona-Lisa. Gandalf is not Odin. Darth Vader is not Darkseid. Ness is not Ninten.