Frisk looks at Marinette, lips pursed. They could help, but... well, meddling was fun, but only if meddling didn't mean burning valuable bridges. "Alright, Mari. Serious mode. Do you actually want my help? I joked about it before, but chances are, I can at least set you up on a date with Adrien." They hold up a single finger, opening their eyes all the way and meeting Marinette stare for stare. "If you agree, you are giving me carte blanche to do what I need to do. On your head be the consequences." Frisk does seem serious. They're always earnest, but they're not playing it up to add to their goofy persona now. This was clearly something that had been bothering their friend for a little while, and they genuinely want to help out however they can.
Frisk is really good at reading people