How about a rly big demon boyfriend?
You said the magic words. Can you guess what the magic words are? You don’t have to because I’ll gladly tell you they’re…really big.
Oh god there are so many good places to go with that though. I don’t know if I can decide on just one concept. Like I love the idea of you accidentally summoning this guy and he’s really way too big for the room you’re in so he has to hunch or like his horns just go straight through the ceiling. And he really tries not to destroy anything as he attempts to move around but it’s completely hopeless and you just have to get used to the fact that you can’t have anything fragile in your life ever again. And because it was an accident for a while you try to figure out how to send him back. But then you two get attached and he’s like “well I can’t really think of anyone else I’d like to spend 70 or 80 years with”. And he’s always apologizing for how big and clumsy he is, but honestly you don’t care because you love him so much.
OR you meet him in a warlock’s dungeon and he’s all chained up (and still massive) and he sneers at you and acts really cold and distant because he thinks all humans are dirt, but eventually he realizes you’re weirdly concerned about him. It freaks him out for a time how sweet you are to him and he’s like “You know what I am right??? You know what I do don’t you???” and you’re just like “Yeah, but that’s okay because you need to do that to survive and most humans who get their soul taken deserve it anyway.” And he’s just baffled. And it’s adorable. And you can tell he’s really conflicted about enjoying your affection because he feels like he’s too evil for this. Eventually the two of you conceive a plan to get him out, but you guys get caught and the warlock is like “Dudes if you wanted to like, be together you could have just asked. I can’t refuse a good romance.” (I don’t know why the warlock is like this. None of his friends know either. He’s weird. We love him anyway.)
OR he’s some kind of like cursed human who became a demon due to vile things in his past. And maybe he like lives in the creepy castles over yonder where you’re always told not to go “or the demon king will eat you” and you’re like psshaw I aint scurred. And you do a dumb and go and get captured and you see him and he’s like a freaking mountain of muscle and you’re like ‘holy shit he’s very attractive to me for some reason???’ And he can tell you’re attracted to him and this peaks his interest so he keeps you around assuming you’ll just be a bit of fun. But then of course he gets attached and when one of his servants goes to make a move on you he completely loses his shit about it. But then he’s like, wait, what if they like my servant better because they’re more human looking? What if they’re better off with them? What if I am not as attractive to them as I thought??? And he’s a big confused demon lord until you guys have a heart to heart and you reassure him you feel very strongly him.
I feel like I could keep going or go really in-depth but I will stop here because I feel good merely having been able to answer an ask at all and I don’t want to burn out.