The pipeline from Frank/Leo/Hazel to Frank/Leo/Nico to Frank/Leo/Bianca is rather steep and sudden. Gay losers and their spooky partner.

seen from Switzerland
seen from Singapore

seen from Malaysia
seen from Lebanon
seen from Venezuela

seen from Maldives

seen from United Kingdom
seen from United States
seen from T1

seen from Norway

seen from Maldives

seen from Norway
seen from United States
seen from India

seen from Germany
seen from United States

seen from Norway
seen from China
seen from Lebanon

seen from Germany
The pipeline from Frank/Leo/Hazel to Frank/Leo/Nico to Frank/Leo/Bianca is rather steep and sudden. Gay losers and their spooky partner.
please tell us more about frabiancleo.... i need to hear how it works in your mind
So you want to hear about frabiancleo, huh? AKA Frank Zhang/Bianca di Angelo/Leo Valdez. Mainly I'm gonna discuss Frank/Bianca and Bianca/Leo because Frank/Leo is a pre-existing relationship.
Frank/Bianca:
In part this stems from me shipping Frank with Thalia, Hazel, and Nico. We don't know a lot about Bianca, because she was only in 2 books (The Titans Curse and The Battle of The Labyrinth), so I extrapolate a large amount of her character from Thalia, Hazel and Nico.
Like Thalia, I picture Bianca having an aptitude for archery (I think this is also canon). And a love for archery is something her and Frank can bond over. Like Hazel, I picture Bianca as occasionally teasing Frank and being family-and-friend oriented. Like Nico, I picture her being quiet and smart, but ultimately kind and fun. I also picture her as being very talented in terms of controlling the dead-- something Nico and Frank canonically bond over in HoH.
Ultimately, I think they would start off as Archery buddies, then advance into close friends due to their interest in undead Roman warriors, and finally get together after a lot of pining on Frank's part.
Leo/Bianca:
Again, this partially stems from extrapolating from me shipping Leo with Thalia, Hazel, and Nico.
Like Thalia, Bianca cannot handle flirting whatsoever, which poses a unique and funny problem in regards to Leo. Like Hazel, Bianca is still adapting to modern life, and I think Leo would introduce her to all sorts of music and movies. Like Nico, I picture Bianca being a nerd-- less geared toward mythomagic, maybe film, music, or literature? -- and maybe she could bond with Leo over that.
More importantly, though, is the unique overlap: Bianca died in Hephaestus's scrapyard and Leo is a son of Hephaestus. I think she would (initially) be very, very wary of Cabin 9, Bunker 9, and The Forge. I picture Leo introducing her to Festus in much the same way as Hiccup introduces Astrid to Toothless in How To Train Your Dragon.
I hope this helps! If you have any other questions/comments, feel free to submit another ask.