FrieAme AU where Friede's a paediatrician and Amethio's a terminally ill inpatient. Friede's in charge of Amethio's care and keeps telling himself not to get attached but oops Friede gets attached. So does Amethio.

Contains main character death, obviously!

Thanks to my good friend for always contributing great ideas! <3

So when Ame was hospitalised he was 15, and when he dies he's 16.

He celebrated his birthday with Frie (of course). Maybe towards the end of Ame's life Spi realises Ame's had a birthday at some point and apologises for never really caring about Ame's birthdays (Ame's fine with it, he doesn't think they're a big deal either)
[Me] Gibe... never picks up on the fact that Ame turned 16 while in hospital
"[Me] Maybe at some point later on Frie casually mentions that he spent Ame's birthday together with him when nobody else would and Gibe's like ""...He had a birthday while in hospital?""

And Gibe realises he doesn't even know when the fuck Ame's birthday is"
"[Me] Gibe knows Spi's birthday is sometime in August, but not the actual date. Ame's?

Ame's could be literally any month of the year."
"[Me] Gibe: When... was this?
Frie: .....Are you seriously asking me when Amethio's birthday was?
Gibe: ...
Frie: February. February 14th. His birthday's Valentine's Day. [Laughs dryly] Isn't that ironic? A day to celebrate love, and there's a boy born on that day who spent most of his life without knowing it..."
"[Me] Gibe: Such ""holidays"" are completely arbitrary
Frie: Maybe. But the irony certainly wasn't lost on him, that's for sure"
"[Me] Gibe: And? Are you trying to tell me that you did stereotypical Valentine's Day things with my son?
Frie: ....Er, n-no, we didn't really. He... He wasn't well enough for that...
Frie: Wait, why do you know how people celebrate Valentine's? Since you don't care and all"
"[Me] Gibe: [Sigh] A certain somebody wanted to spend that day with me, many decades ago. I still do not understand the purpose of the festivities, but... I can't say I look back on that day negatively
Frie: So you're saying you had fun
Gibe: ...Silence"
[Me] Frie: I know I shouldn't be asking this, but... Is that another reason you resented Amethio? That he was born on a day you had fond memories of spending with the person you wished to spend your life with? And that Amethio being born that day... was yet another reminder of what you couldn't have?
"[Me] Gibe: No. I never made that connection. By the time he was born, I had all but forgotten about things such as Valentine's. Those memories had long since been sealed away.
Gibe: The day he was born is irrelevant. I do not believe in such superstitions or whatever you wish to call them. It was simply the fact that he was born at all."
"[Me] Frie: ...Right...
Gibe: I do not expect you to understand. I myself am aware that there is no reason to resent Amethio for his own existence. In many ways, I... was trying to blame someone else. Anyone but my own pathetic, cowardly self
Frie: ..."
"[Me] Frie: Amethio... said that he never celebrated his birthday. Your family doesn't do that, and he had no friends to spend time with. Most kids his age would've been at least having a small group of friends over for a meal or something...
Gibe: That's not... entirely true
Frie: Oh?"
"[Me] Gibe: His mother used to celebrate his birthday. And Spinel's. She would buy them some ridiculous gift, dress them up, and let them eat whatever they wanted throughout the day. I never approved, but she insisted.
Gibe: However, I suppose Amethio was too young when she left to remember any of it..."
"[Me] Frie: ...Did you never even buy them presents?
Gibe: Money was never a concern, so if they had wanted something, they simply would have asked
Frie: And if Amethio had asked for something for himself, would you have let him buy it?
Gibe: Yes. He had his own computer, a phone, many books, and I believe even some kind of gaming device"
"[Me] Gibe: He never asked for much, but he had what he wanted. Unlike Spinel, who would constantly purchase things online...
Gibe: Actually. Spinel still does that. Not that it's any of my concern, I suppose"
"[Me] Frie: I would have thought you wouldn't've let him...
Gibe: It would entirely depend on what he was asking for. Of course, I would never allow him to buy anything inappropriate. Or impractical. But he never requested such things, so I had no reason to deny him.
Frie: ..."
"[Me] Frie really doesn't understand Gibe. But it doesn't matter anymore, since Ame's not there.

Frie at least knows the feeling of not having your birthday celebrated. His parents were like that, too. But as an adult, Frie always celebrates his birthday. He gets together with his friends and they enjoy themseleves."
[Me] Also Frie realises that in addition to not understanding Gibe, he really has no fucking idea how rich families work lmao
[Redacted] Oh no... Ame's birthday being ironic... Gibe not remembering it...
[Me] Amethyst is the birthstone for February too so it works perfectly lol (Spi's birthday is in August for the same reason. I love basic-ass symbolism like this)
"[Me] I like to think their mother named them in this AU... And she did it on purpose.

Like, she specifically named Ame after his month's birthstone and Gibe A) couldn't give less of a shit about such things and B) why would he remember Ame's birthday"