You mentioned in your last ask when Black began developing feelings for Lissa and it made me wonder when the others on the crush list started developing feelings?
That's easy enough to answer!
Black - When Lissa chose to sit next to him instead of Blue. He felt seen and like he was the first pick for once. It made him see her differently. Hearing her confirmation that she wanted to sit next to him made him feel for once in his life like he wasn't completely worthless and unwanted.
Wolf - When she called him Papyrus for the first time. Like with his older brother, he felt seen. That Lissa had the respect to know he was his own person but that he was still Papyrus and that he might still want to hear his name sometimes.
Coffee - When she got under the blanket with him when he was upset after the incident with Wine. Lissa understanding he was overwhelmed and overstimulated, got under the blanket instead of forcing him out of it. She quieted the loud world around him and she listened to his explanation, but also forgave him. This meant a great deal to him.
Money - When she saved him from the scolding Toriel was giving him at the pool. She stepped in when he should've been chewed out. Lissa took the unprompted yeeting with grace and not only that but she called him by his actual name then nickname. He realized she actually likes him for exactly who he is and he was hooked.
Edge - When they went to the cooking lesson. Edge realized he liked flirting with her and that she was genuinely trying to get to know him. She picked an activity that he would enjoy, not necessarily herself. She put him before herself which was a novelty in his universe. He loved talking to her and saw the care she put into their relationship. At the end of the lesson, he was the one cooked.
Stretch - When she defended him from Brad and comforted him afterwards. She made him feel important and wanted. For the first time, he didn't feel like a clumsy fool, especially after she comforted him. He realized she genuinely sees him, and adores him as he is and that made him fall hard.
Sparrow - When he was in heat and she helped with his back, then made sure he knew he was handsome. Sparrow had felt self conscious for so long that he doesn't think he is attractive at all or deserves good things, especially after all he's done. However, Lissa accepts those things, loved them anyway and hearing her so passionately tell him that he's handsome and she wouldn't hear anything else about it, slammed it home for him that she's the one.
Wine - When she broke into his room. She came not to yell at him, but to apologize and forgive him. He didn't think he deserved it that she would be in the right to never speak to him again and that actually frightened him. The thought of losing someone like that and someone who actually cared about him? Her forgiveness, her gentle kindness got him in that moment and he was hers.
Red - When they went to the movies. Red was a bit oblivious to his own feelings until he kissed her and marked her cheek. He realized in that moment that he felt so overwhelming protective of her that it actually took him aback. Red didn't even notice how she'd crept her way into being someone he doesn't think he can go a day without seeing. He now knows he's epically screwed but is hoping that he can pretend nothing has changed.