Leto's Links
His super cool, knowledgeable mentor. Leto admires Rey a great deal, constantly seeking his opinions and approval, even if he's terrible at expressing it. With his parents gone, he views his teacher as something of a substitute paternal figure. Not that he will admit that.
Leto is very eager to get on the witch's good side, and get his hands on her magical knowledge however he can. To him, no price is too steep to further his magical skills. Unfortunately, he's too much of a dingus to realize she's milking him.
Luna has no problem with sharing all the knowledge she's gattered through years of magical research. For a price.
While Leto might not be the most wealthy individual to step by her door, he surely can repay her through some other ways. Since Leto is a traveler, they've gotten a deal: he brings her all kinds of ingredients from around Jo'Arca, which she uses on her potions and she gives him the information he needs. The witch never said how long it would take however.
Sponsor to Leto's engeneering shit and his crazy idea of time traveling or something... Aria doesn't understand much about what the creative young crafter is doing, but it sounds fun and she supports it! If it's an invention that can help others, she's totally in for the ride ~
"They seem kind of strange, and sometimes they say odd things. BUT!! It's seems like they know about time magic so I AM ON IT"