so Guest and Bakugo have a gay strong dark romantic relationship, they are both possessive over each other but then there’s this girl named Sonata who has a Cupid quirk that can make anyone fall in love with her and who believes their too toxic for each other, she is very determined, cruel and obsessive. So she does anything to break them up.

So Guest was walking casually to head into the restroom and the girl secretly followed him, clearly planning something. When Bakugo was walking to class, Sonata grabbed Guest by the collar and kisses him as she uses her Cupid quirk to make Guest fall in love, and it works....though it's not real love. Guest falls in love immediately a his eyes shine pink then fad to his normal eye color. Not realizing how hurt Bakugo is. Bakugo turned to a different direction and tears threatened to fall.

The next day, Sonata and Guest were officially a couple, everyone unaware Guest is under a love effect and is awfully submissive for her. Which is weird, he was never like that for Bakugo, only dominance but never like this. But anyway the 'couple' were sitting together in class1-A and paying attention to the lesson.