You know when you're just trying to spend some alone time together and there's always someone there to ruin the moment? Yeah. Here's that.
Either Satan or Diavolo so it comes in two flavors.
Either it's Satan actively waiting to pounce at just the right moment to keep his brother from getting anywhere (Oh, what's that Lucifer? You have tomorrow off? I've already invited the MC to an art exhibit… We'll be gone a while so don't wait up. 😏)
Or it's Diavolo innocently crashing the party because he needs XYZ task done or just wants Lucifer for tea (and he won't settle for "No, I'm busy" either 😣)
Asmo seems to have a sixth sense for when his brother is planning to do something with the MC and he won't have it. He'll tail them and crash their dates without a lick of shame.
Levi just has a nasty habit of coming to collect on his debts whenever Mammon is just starting to get comfortable, and that includes being with the MC… Things become a lot less romantic and more stressed when you're running from an angry demon... 🤷♀️
Mammon, but mostly himself…
Poor boy's nerves are his greatest enemy. He can have the perfect date or romantic gesture planned out in his head but the second he has the chance to do it, he aborts the idea entirely.
It doesn't help that Mammon always starts getting really needy whenever Levi starts making some headway… Soon the MC is off to go babysit him while Levi's stuck sticking more pins into his Mammon voodoo doll…
Belphie never actively tries to cockblock Satan, he just tends to turn up at all the wrong moments. Usually, Satan has the misfortune to be with the MC and not realize that Belph is napping nearby. So the two get interrupted by his sudden return from Dreamland then, of course, he won't leave… 🙄
Lucifer 100% puts effort into it though, just more subtly. He'll make surprise changes to the MC's schedule or ask them to do emergency "tasks…" whenever he knows Satan's making plans… Payback is a bitch, ain't it? 😏
Mammon has zero trust that Asmo will remember the human is "his" so he stalks their dates about as much as Asmo stalks his. He's also not above making off with the MC when Asmo isn't looking like he's pulling off some kind of rescue/heist… That puts a new spin on things if nothing else. 🤷♀️
It's inevitable that if you go out shopping for a while that you'll probably bump into Beel getting food. The sweetheart doesn't mean to crash things, it's just that he's so sweet that even Asmo has a hard time telling him to get lost so he'll just follow them around like a big puppy… 😓
If Beel had an arch-nemesis it would probably be his own stomach… There are so many times where he'd like to just sit and cuddle or have a nice night without having to make 3 separate runs to the kitchen but that's just not possible… Hopefully the MC is patient with him. 😣
Meanwhile, Beel is usually the first person Belphie looks for when he wakes up so of course he's walked in on them a lot. Again, not really on purpose, but like he's just going to leave his two favorite people alone once he finds them, you know?
Belphie jokes a lot that he hates his brothers and this is part of the reason why. He'd love to just be left alone to laze around all day, but they've always got to bother him with something…
He gets particularly irritated when they mess with his MC time. If he could lock himself and the MC back up in the attic then go back to pretending he's gone, he'd probably do it. (Well, he may give Beel the key but past that screw everybody else! Leave us alone, damnit!!)