Why is it that only Kagome and Inuysha can only go through the well, and some other demons what makes them so special?

because kagome is apart of that time and she unsealed inuyasha

I believe it's the jewel shards that allow them passage, but other then that I've always believed it was the enchanted beaded ہار he wears that allowed Inuyasha to pass through the well to Kagome's time. It's connetted to Kikyo's soul, because she was the one who enchanted it to be used on him originally, which لنکس him to Kagome who currently holds the spell, and that connection allows him to follow after her.

An easy example of this is in episide 3 "Down the Rabbits Hole and Back Again" Inuyasha, without any jewel shards on his possession lept through the well after Kagome so he could drag her back to his time. To me that کہا enough.

About the demons being able to pass through it I believe this only happened twice in the story. The first time was when Kagome was caught سے طرف کی the Mistress centipede کی, کنکھجورا, ہزارپا and got dragged to the Feudal Era in episode 1, but we learned later on (in a filler episode of course) that the centipede کی, کنکھجورا, ہزارپا pased through the well because of her bones that were thrown in the well after she had been slane. Her soul apparently went with them, some how sensed the Shikon Jewel in another time zone beyond it and struck out and nabbed Kagome. The سیکنڈ time a demon passed through, wasn't actually a real passage either, but was when Yura of the Hair was persuing Inuyasha and a strand of her hair was clong to his کیمونو, kimono when he passed through unwittingly bringing her hair along with him. I don't think her hair would have been able to pass through other wise. Although she did have a jewel shared in her possession at the time as well. The one she چرا لیا, چوری کی from Kagome in the گزشتہ episode. *oopse* ترمیم ^^

well all i know is that kagome can travel through the bone eaters well because of:
1)she is the reincarnation of kikyo.
2)she carries shikon jewel shards

well inuyasha? not sure. but here is my theory:
1)i remember one time (not the ep like 18. the one where inuyasha takes kagome's jewel shard after first meeting naraku) i saw him pulling the little jar of shards out of his kimono. but kagome was اگلے to him wearing her giant shard with her.

as for other demons? not sure. i guess that how rumiko takahashi wanted it. maybe she thought that would go with the situation and story line. who knows

The Shikon no tama can open the passage. When they lose the fragments of the shikon jewel they can no longer pass trough. In some cases they can pass without the jewel but that is because they have been "contaminated" سے طرف کی the quantic state of the other time period.