You and Chat Noir were training together because you had just received a Miraculous and he offered to train with you. However, you know each other's secret identities, as you also know each other in real life and are practically best friends. This is also one of the reasons why you have a Miraculous: Adrien put in a good word with Ladybug, she met you, and gave you one. (Choose one or make up your own)

While training, you heard a bang, and suddenly a supervillain appeared in the distance. Ladybug and Rena Rouge were already on their way. You and Chat Noir exchanged a quick glance and then joined the fray.

The battle lasted a while, but Ladybug's plan was to split into teams of two and observe the situation. You and Chat Noir discussed the situation briefly and then suddenly said the same thing.

You grinned at each other, said the next thing, and then said the same thing again.

"Two fools, one thought, eh?" he says, and you both laugh a little, then look at each other and just smile.

Before you move closer and suddenly kiss.

After the kiss, you look at each other for a moment before both scratching your heads.

"Uhmm... That was a bit unexpected..." he says, and you can only nod.