Ace first uses his medium powers

Life, Supernatural

Ace first sees the ghosts of his ancestors, Gellert Grindelwald and Albus Dumbledore having tea at the graves he visited for the first time. He however said nothing about it to his family, not wanting Felix to have more ammunition to make fun of him. He returned the next day, however, asking them questions, since then Gellert has been following Ace around for a while, while Albus hasn't appeared since he entered Hogwarts.

Mediums are rare in the wizarding world, it has been unheard of since the 18th century, a lot is unknown about how mediumship came to be or if it was inherited or was because of some psychological change or just a talent that finds someone like a seer, though Gellert Grindelwald's children had no seer capabilities and neither did Ace.   Mediums can communicate with spirits or ghosts, there are two types of ghosts, one with a semi-corporeal body, the other has moved on to the afterlife but a semblance of a spirit remains where they do not have memories of their previous life but have feelings about certain things, like a premonition or deja vu, they can still feel if something is bad or good. Once a medium connects with their spirit, the spirit is able to leave their spot usually it is either near their body or near what they hold most dear, a medium can also restore a spirit's memories.   Ace only talked to them like his imaginary friends until he was old enough to research what it was. Gellert was the one who suggested he took the Deathly Hallows to rule the wizarding world or have it destroyed.