The Greeed of Kamen Rider OOO, assuming that you have all 5 together, that has Mezool as the mother-type, Gamel as the borther-type and Kazari, Uva and Ankh sharing the uncle/father type, because none of them are trustworthy enough.
Maybe have them start to speculate in the second year (or before if Parsletounge comes up before then) that Harry might have on of the orange (Repltile) medals. (For those who don't know about them but do know about OOO, one of the medals is a snake medal)