Fred Weasley.

Fred Weasley, a year older than Hermione, is in his 5th year, she is in her 4th. The Triwizard Tournament was currently taking place, and he is too old to participate. He and his brother prepared a potion and wanted to break the age-based ban that Dumbledore had set.
Fred ran up to Hermione and put his arm around her shoulders.

• My girl, we came up with something so amazing, you'll be amazed.

He kissed her on the cheek.