Are there any fanfics out there that combine the Agent Bonbon idea with the "Bonbon is a changeling" fanon? While I am not a fan of the former on it's own, I do think it could be interesting if mixed with that piece of fanon.

Not that I know of, but there is one in which the wedding changeling was her partner.

Not yet. I mean, Slice of Life may hav been aired almost a year ago, but I haven't seen anyone try to crossover this YET . I am in the process of making a story arc based on agent Bon, but also features changelings in one encounter . I have better things in mind for my fic. Something much darker , but isn't considered Tragedy cuz if I kill Bon, it would lose its other purpose . A LyraBon fic

I think rhe prologue will come out next week if I'm not busy. So if you're interested, I'd be glad to give you an origin story which is dark and features LyraBon, I also have other things featured in it, but I dare not say since it would be a spoiler