LV - ugly baby

[Tonks]

No: HPFGUIDX 125022


Does anyone have any idea how it is that LV lost his body, became 
vapor and later appears as an ugly baby in the graveyard??  If he is 
mist, where did this physical baby thing come from?  And what is it? 
At one point I thought it was an Incubus, but I really don't know 
much about them and I am not sure if they look like a baby. What is 
the ugly baby thing??  

Tonks-OP