Is The Potter's Invisibility Cloak A Relic?

[Ken Hutchinson]

No: HPFGUIDX 158301

A relic of Ravenclaw or Gryffindor that is. Weren't some of the
memories that DD shows Harry in HBP collected well before the attack
at Godric's Hollow? DD had concerns about Tom Riddle for a long time,
almost from the beginning. Surely he would have suspected him of
creating a horcrux, possibly he suspected him of creating multiple
horcruxes even by the time of the GH attack. At that time he might
been aware of Tom's fascination with relics of the Founders and might
have suspected that Tom intended to make four horcruxes from four
relics. Knowing that the Potters were targets he might have convinced
James to give him the cloak, just in case. LV might have known of the
cloak and might have been intending to make it into a horcrux with
Harry's death that very night. 

When Harry gives DD Riddle's destroyed diary DD realizes with a shock
that LV must have created more than four horcruxes, or intended to.
But how many? This would have given DD a new quest to pursue before he
could start the process of destroying all the horcruxes and
eliminating LV for good. That quest lead him to Slughorn and the need
to collect his memory of Riddle's horcrux question.

Unfortunately I don't have the books with me and so parts of this
might not wash with canon. But it is conceivable that even before the
GH attack DD at a minimum had some vague suspicions about Tom's
fascination with the Founder's relics and wanted to protect James's
cloak from him even if DD didn't fully understand what Tom was doing
with the relics. It would be like DD to tell Harry that the sword was
the only "known" Gryffindor relic, "known" as in generally known,
while knowing himself that there was another. This is a covert
activity and DD has to keep his cards close to his chest. One of DD's
failings is that he keeps his cards secret too long from people who
need to know. If the cloak is a relic of either founder and DD knew it
his failure to disclose that will probably cost Harry some kind of
trouble in book 7. But that is exactly the kind of mistake that DD
*would* make.

Ken