(Mmmmm I’m gonna answer these as a “what makes them realize they are in love with their S/O”. I’m pretty sure I’ve down confession headcanons in the past for them.)
Honestly, Allen falls in love all at once. It hits him like a splash of cold water.
He sees you one morning, and you’re talking to somebody, and he’s watching your little unconscious mannerisms and ticks and realizes, “I’m in love with them.”
At first he’s a little shocked–he didn’t exactly wake up thinking he was going to have that revelation today, but here he is. And then he smiles, because he’s okay with it.
He comes over and sits by you and when you ask him what the smile’s for he just hums and shrugs, gazing at you in awe. It’s a good look for him, though, him being lovestruck.
Kanda would take a long time to realize he’s in love with you, and it’s your patience that seals the deal.
You’ve stuck around with him this long, but that’s not it. You are patient with him even when he’s being an ass, or when he’s confused and lost.
He thinks you are a saint and the love he has for you is so strong it hurts and kind of scares him.
And then you smile at him and that’s it, he’s gone. RIP Kanda
Lavi falls in love with your spirit. Your smile, your laugh, your life. He thinks you are a goddamn blessing and like Kanda, he’s terrified.
Bookman aren’t suppose to have a heart and it’s like you stepped in and every glance, every gentle touch, every giggle and whispered uttered has filled his empty chest with warm love.
And he’s happy. So happy. He could cry. He doesn’t. But he could.
He’s conflicted. This really threw his plans out the fucking window. How is he going to be able to leave you now that he knows he loves you so much? It would kill him.
Lenalee falls in love with your strength. Not just physical strength, but your mental and emotional strength.
She’s always been worried that she wasn’t strong enough, and next to you, she realizes that that wasn’t the case; you make her realize that she was just strong in her own way, just like you were strong in your own way.
It makes her happy. You make her happy. She really wants to spend the rest of her life with you, no matter how long or short it may be.
She also falls in love with the way that you get along with Komui. She was afraid he would scare you off, but yet here you are, still with her.
Link falls in love with your gentleness. He’s so used to being surrounded by rough and tough characters–a lot of which seemed heartless–that he feared that he, too, would become like them.
And then here you come waltzing into his life, tugging out his inner kindness and gentleness.
The gentle way you seem to chip away at his rough exterior with a metaphorical chisel, breaking a part his protective wall and letting his feelings ooze out.
He realizes this when he’s making you your nth packed lunch in the early hours of the morning. His hands freeze as the realization dawns upon him, and he needs a moment to just breathe.
Toad's Cave 