Mr. "surroundedbyperverts" what are some of your favourite Marco "Crack Ships"? as in charactes that haven't had any interaction with Marco at all? mine is Sabco (Sabrina + Marco)
The specific type of Crack Ship your ask defines is similar to what is known by tropers such as myself as Ships That Pass in the Night. Based on the definition you have provided, some of the passing ships I enjoy between characters who barely interact include the aforementioned Sabco (Sabrina Backintosh × Marco Diaz), Hopeco (Hope Hadley × Marco Diaz), Britco (Brittney Wong × Marco Diaz), Chanco (Chantal × Marco Diaz), Leahco (Leah × Marco Diaz), and a very specific variation of Moonco (Moon Butterfly × Marco Diaz) that involves a temporally displaced duplicate of her teenaged self. I also ship Marco with Daniella (the blonde girl from Belgium who was the Diaz family’s first exchange student and who was briefly seen in a photograph in “The Other Exchange Student” kissing Marco on the cheek), but it can be presumed that they have had significant interaction prior offscreen even if the audience has yet to see her in person.
As for Crack Ships that are illogical for reasons other than lack of substantial interactions, I have a few. I don’t fully ship Tomco (Tom Lucitor × Marco Diaz) myself (and I think that the pairing is arguably not quite as crack as it once was), but I do headcanon that Tom developed an unrequited crush on Marco. Going beyond that, I also headcanon that Marco eventually meets Mabel Pines from Gravity Falls and becomes one of her new crushes.
Going beyond even Crack Ships that involve Marco specifically, my biggest one is Mortentence. That’s the ship name I just made up for my pairing of Elizabeth Butterfly a.k.a. Elizabeth Karatentence (@moringmark’s OC Starco daughter from his Ship War AU comic) and Morty Smith from Rick and Morty. I also have an extremely convoluted headcanon that Mermando from Gravity Falls is somehow the cute guy from skate camp that Jackie-Lynn Thomas mentioned having a crush on in “Sleepover” during the Truth or Punishment game.
Leah Marcos - also known as mini!BAMF (she’s essenitally the first BAMFini before the fandom got overrun by Taylor/Wash kids). Many see in her a rip-off Newt but I think, she’s a lot more than just that. Leah is blackmailed by Mira into getting the box and you can see how sorry she is for betraying Taylor, Wash and Jim, but she has no choice, she did it for her brother and that tells us so much about her. I already had forgiven her at the end of the episode but then she played ‘Wash’ in 1x09 'Vs’ and that sealed the deal for me. There’s nothing cuter than that. xD
“Hey, you’re safe here Leah. No one gets through those gates unless Taylor says so” Josh told Leah while he thought about how he could murder Zoe and Leah and make it look like a sixer attack gone wrong. Then in the grief of the kids deaths he could comfort his precious Maddy…