Feeble child-thing in train station (From Deathly Hallows)

[aquilalorelei]

No: HPFGUIDX 173894

Nothing spoilery in the title, nosirree.  
Just wondering what we think the flayed piteous child-thing is in the
limbo!King's Cross station.
I really have no idea, especially with why Dumbledore so specifically
forbids Harry to aid it (him? her?) Was it a part of Tom Riddle, and
so would corrupt Harry with its evil?  Was it something of Dumbledore
or his family that he did not want Harry to see?  Was it a part of
Harry himself best left unexplored?
And last but perhaps most importantly, why was it there if it had
nothing to do with Harry when, presumably, the "vision-space" was his?
Discuss.

Regards,
AquilaLorelei