Harry and Eggsy loves eachother, but no one tells the other! Merlin and Roxy notices of course and they annoy Harry and Eggsy about it until the day Eggsy gets enough and does what he "should've" done weeks ago.
This is a monumentally bad idea, Eggsy realizes, in the fraction of a second between reaching out and tugging at Harry's tie and seeing his eyes briefly widen before their lips meet. Snogging is a great distraction technique for hiding in plain sight from your enemies. It is decidedly not great for hiding your growing...